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Balthazart J, Roselli CE. Hormonal, Genetic, Immunological: An Array of Mechanisms but How Do They Interact, If at All? Arch Sex Behav 2023; 52:2963-2971. [PMID: 36376746 DOI: 10.1007/s10508-022-02469-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 10/28/2022] [Accepted: 10/30/2022] [Indexed: 05/20/2023]
Affiliation(s)
| | - Charles E Roselli
- Department of Chemical, Physiology & Biochemistry, Oregon Health & Science University, Portland, OR, USA
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2
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Bragazzi NL, Converti M, Crapanzano A, Zerbetto R, Siri A, Khamisy-Farah R. Probing the genomic landscape of human sexuality: a critical systematic review of the literature. Front Genet 2023; 14:1184758. [PMID: 37693319 PMCID: PMC10483070 DOI: 10.3389/fgene.2023.1184758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 07/31/2023] [Indexed: 09/12/2023] Open
Abstract
Whether human sexuality is the result of nature or nurture (or their complex interplay) represents a hot, often ideologically driven, and highly polarized debate with political and social ramifications, and with varying, conflicting findings reported in the literature. A number of heritability and behavioral genetics studies, including pedigree-based investigations, have hypothesized inheritance patterns of human sexual behaviors. On the other hand, in most twin, adoption, and nuclear family studies, it was not possible to disentangle between underlying genetic and shared environmental sources. Furthermore, these studies were not able to estimate the precise extent of genetic loading and to shed light both on the number and nature of the putative inherited factors, which remained largely unknown. Molecular genetic studies offer an unprecedented opportunity to overcome these drawbacks, by dissecting the molecular basis of human sexuality and allowing a better understanding of its biological roots if any. However, there exists no systematic review of the molecular genetics of human sexuality. Therefore, we undertook this critical systematic review and appraisal of the literature, with the ambitious aims of filling in these gaps of knowledge, especially from the methodological standpoint, and providing guidance to future studies. Sixteen studies were finally retained and overviewed in the present systematic review study. Seven studies were linkage studies, four studies utilized the candidate gene approach, and five studies were GWAS investigations. Limitations of these studies and implications for further research are discussed.
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Affiliation(s)
- Nicola Luigi Bragazzi
- Laboratory for Industrial and Applied Mathematics (LIAM), Department of Mathematics and Statistics, York University, Toronto, ON, Canada
- Postgraduate School of Public Health, Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy
- United Nations Educational, Scientific and Cultural Organization (UNESCO) Chair, Health Anthropology Biosphere and Healing Systems, University of Genoa, Genoa, Italy
| | | | - Andrea Crapanzano
- Department of Counseling, San Francisco State University, San Francisco, CA, United States
| | | | - Anna Siri
- United Nations Educational, Scientific and Cultural Organization (UNESCO) Chair, Health Anthropology Biosphere and Healing Systems, University of Genoa, Genoa, Italy
| | - Rola Khamisy-Farah
- Clalit Health Services, Akko, Israel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
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3
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Johnson L, Lukert B. Science, Scripture, and Sexuality: The US United Methodist Church at Crossroads. J Relig Health 2023:10.1007/s10943-023-01806-7. [PMID: 37079172 PMCID: PMC10117265 DOI: 10.1007/s10943-023-01806-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/21/2023] [Indexed: 05/03/2023]
Abstract
During the past 50 years, medical and behavioral scientists have made great progress in understanding the variables which influence the development of sexual orientation, identity, and consequent behavior. In most instances, homosexuality is influenced by hormonal, genetic, and immunologic variables during fetal development, and the effects cannot usually be altered without consequence. The recent struggle within The United Methodist Church in the USA reflects the difficulty that society in general has with accepting homosexuality as part of the spectrum of sexuality. Hopefully, understanding the factors influencing sexual orientation will aid in reducing prejudice and eventually bring an end to the pain endured by the LGBTQ community, and the conflict within The United Methodist Church, a prototype of the struggle.
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Clemens B, Lefort-Besnard J, Ritter C, Smith E, Votinov M, Derntl B, Habel U, Bzdok D. Accurate machine learning prediction of sexual orientation based on brain morphology and intrinsic functional connectivity. Cereb Cortex 2023; 33:4013-4025. [PMID: 36104854 PMCID: PMC10068286 DOI: 10.1093/cercor/bhac323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Sexual orientation in humans represents a multilevel construct that is grounded in both neurobiological and environmental factors. OBJECTIVE Here, we bring to bear a machine learning approach to predict sexual orientation from gray matter volumes (GMVs) or resting-state functional connectivity (RSFC) in a cohort of 45 heterosexual and 41 homosexual participants. METHODS In both brain assessments, we used penalized logistic regression models and nonparametric permutation. RESULTS We found an average accuracy of 62% (±6.72) for predicting sexual orientation based on GMV and an average predictive accuracy of 92% (±9.89) using RSFC. Regions in the precentral gyrus, precuneus and the prefrontal cortex were significantly informative for distinguishing heterosexual from homosexual participants in both the GMV and RSFC settings. CONCLUSIONS These results indicate that, aside from self-reports, RSFC offers neurobiological information valuable for highly accurate prediction of sexual orientation. We demonstrate for the first time that sexual orientation is reflected in specific patterns of RSFC, which enable personalized, brain-based predictions of this highly complex human trait. While these results are preliminary, our neurobiologically based prediction framework illustrates the great value and potential of RSFC for revealing biologically meaningful and generalizable predictive patterns in the human brain.
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Affiliation(s)
- Benjamin Clemens
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
- Research Center Jülich, Institute of Neuroscience and Medicine: JARA-Institute Brain Structure Function Relationship (INM 10), Wilhelm-Johnen-Strase, 52428 Jülich, Germany
| | | | - Christoph Ritter
- Interdisciplinary Center for Clinical Research (IZKF), RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Elke Smith
- Biological Psychology, Department of Psychology, University of Cologne, Bernhard-Feilchenfeld-Str. 11, 50969 Cologne, Germany
| | - Mikhail Votinov
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
- Research Center Jülich, Institute of Neuroscience and Medicine: JARA-Institute Brain Structure Function Relationship (INM 10), Wilhelm-Johnen-Strase, 52428 Jülich, Germany
| | - Birgit Derntl
- Department of Psychiatry and Psychotherapy, University of Tübingen, Calwerst. 14, 72076 Tübingen, Germany
- Werner Reichardt Center for Integrative Neuroscience (CIN), University of Tübingen, Otfried-Müller-Str. 25, 72076 Tübingen, Germany
| | - Ute Habel
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
- Research Center Jülich, Institute of Neuroscience and Medicine: JARA-Institute Brain Structure Function Relationship (INM 10), Wilhelm-Johnen-Strase, 52428 Jülich, Germany
| | - Danilo Bzdok
- McConnell Brain Imaging Centre, McGill University, 3801 University Rue, Montreal Quebec H3A 2B4, Canada
- Department of Biomedical Engineering, McGill University, 3775 University Rue, Montreal Quebec H3A 2B4, Canada
- Faculty of Medicine, Montreal Neurological Institute (MNI) and Hospital, McGill University, 3801 University Rue, Montreal Quebec H3A 2B4, Canada
- Mila–Quebec Artificial Intelligence Institute, 6666 Rue St-Urbain #200, Montreal Quebec H2S 3H1, Canada
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5
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Jiang Y, Yang F. Bridge of Rainbow: Association Between Internet-Based Social Media Use and Homosexuality Inclusion in China. Front Psychol 2022; 13:882206. [PMID: 35783764 PMCID: PMC9243644 DOI: 10.3389/fpsyg.2022.882206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022] Open
Abstract
By using the nationally representative dataset of China Labor-force Dynamics Survey, this paper explored the relationship between internet-based social media use and Chinese people's homosexuality inclusion. Addressing endogeneity by using an instrumental variable approach, the results of instrumental variable-ordered probit model indicated that individuals' internet-based social media use had a positive and significant association with their homosexuality inclusion. Furthermore, the heterogeneity analysis revealed that the heterogeneous effects of internet-based social media use on homosexuality inclusion caused by income, gender, and region. The homosexuality inclusion of respondents with higher income, respondents of female gender, and respondents located in eastern region of China was found to be more evidently associated with internet-based social media use. The functional mechanism analysis suggested that the number of respondents' LGBT friends mediated the overall relationship between internet-based social media use and homosexuality inclusion. The robustness check showed that the results were robust cross different models. The findings in this paper provide new evidence that the effect of information technology development on individual perception and behavior in Chinese context.
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Affiliation(s)
- Yao Jiang
- Zhou Enlai School of Government, Nankai University, Tianjin, China
- *Correspondence: Yao Jiang
| | - Fan Yang
- Department of Labor and Social Security, School of Public Administration, Sichuan University, Chengdu, China
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6
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Abstract
Since the 20th century, multiple studies have linked the variations in human sexual orientation, from heterosexuality to bisexuality or homosexuality, to a wide range of biological factors. However, a clear mechanism that leads to the development of these variations has not been established yet. This review consolidates various comprehensive studies on the possible biological factors in the fields of genetics, epigenetics, uterine environment, hormones, neuroanatomy, and neurobiology that lead to these variations. One intriguing question that 'homosexuality phenotype' faces is its ability to avoid elimination by Darwinian selection. This review tries to explain why natural selection is not eliminating the genetic factors associated with homosexuality even at the cost of the evolutionary fitness of homosexual individuals. Studies supporting certain strong candidates for alternative sexual orientation (ASO) are highlighted, which can become new research avenues for investigators in this field. Further, a novel speculation is proposed that might be contributing to the development of variation in human sexuality.
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Affiliation(s)
- Sidhant Jain
- Department of Zoology, University of Delhi, Delhi, India
| | - Meenakshi Rana
- Department of Zoology, University of Delhi, Delhi, India
- Dyal Singh College, University of Delhi, Delhi, India
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7
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Sanders AR, Beecham GW, Guo S, Badner JA, Bocklandt S, Mustanski BS, Hamer DH, Martin ER. Genome-Wide Linkage Study Meta-Analysis of Male Sexual Orientation. Arch Sex Behav 2021; 50:3371-3375. [PMID: 34080073 PMCID: PMC8604844 DOI: 10.1007/s10508-021-02035-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 05/01/2021] [Accepted: 05/04/2021] [Indexed: 05/26/2023]
Abstract
Male sexual orientation is a scientifically and socially important trait shown by family and twin studies to be influenced by environmental and complex genetic factors. Individual genome-wide linkage studies (GWLS) have been conducted, but not jointly analyzed. Two main datasets account for > 90% of the published GWLS concordant sibling pairs on the trait and are jointly analyzed here: MGSOSO (Molecular Genetic Study of Sexual Orientation; 409 concordant sibling pairs in 384 families, Sanders et al. (2015)) and Hamer (155 concordant sibling pairs in 145 families, Mustanski et al. (2005)). We conducted multipoint linkage analyses with Merlin on the datasets separately since they were genotyped differently, integrated genetic marker positions, and combined the resultant LOD (logarithm of the odds) scores at each 1 cM grid position. We continue to find the strongest linkage support at pericentromeric chromosome 8 and chromosome Xq28. We also incorporated the remaining published GWLS dataset (on 55 families) by using meta-analytic approaches on published summary statistics. The meta-analysis has maximized the positional information from GWLS of currently available family resources and can help prioritize findings from genome-wide association studies (GWAS) and other approaches. Although increasing evidence highlights genetic contributions to male sexual orientation, our current understanding of contributory loci is still limited, consistent with the complexity of the trait. Further increasing genetic knowledge about male sexual orientation, especially via large GWAS, should help advance our understanding of the biology of this important trait.
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Affiliation(s)
- Alan R Sanders
- Department of Psychiatry and Behavioral Sciences, NorthShore University HealthSystem, 1001 University Place, Evanston, IL, 60201, USA.
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
| | - Gary W Beecham
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Shengru Guo
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | | | - Sven Bocklandt
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brian S Mustanski
- Department of Medical Social Sciences, Northwestern University, Evanston, IL, USA
| | - Dean H Hamer
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Eden R Martin
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
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8
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Hu SH, Li HM, Yu H, Liu Y, Liu CX, Zuo XB, Lu J, Jiang JJ, Xi CX, Huang BC, Xu HJ, Hu JB, Lai JB, Huang ML, Liu JN, Xu DG, Guo XC, Wu W, Wu X, Jiang L, Li M, Zhang GP, Huang JW, Wei N, Lv W, Duan JF, Qi HL, Hu CC, Chen JK, Zhou WH, Xu WJ, Liu CF, Liang HY, Du J, Zheng SF, Lu QL, Zheng L, Hu XW, Chen FX, Chen P, Zhu B, Xu LJ, Ni ZM, Fang YZ, Yang ZK, Shan XR, Zheng ED, Zhang F, Zhou QQ, Rao Y, Swaab D, Yue WH, Xu Y. Discovery of new genetic loci for male sexual orientation in Han population. Cell Discov 2021; 7:103. [PMID: 34719679 PMCID: PMC8558329 DOI: 10.1038/s41421-021-00341-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 08/31/2021] [Indexed: 12/12/2022] Open
Abstract
Epidemiological studies have demonstrated that the genetic factors partly influence the development of same-sex sexual behavior, but most genetic studies have focused on people of primarily European ancestry, potentially missing important biological insights. Here, we performed a two-stage genome-wide association study (GWAS) with a total sample of 1478 homosexual males and 3313 heterosexual males in Han Chinese populations and identified two genetic loci (rs17320865, Xq27.3, FMR1NB, Pmeta = 8.36 × 10-8, OR = 1.29; rs7259428, 19q12, ZNF536, Pmeta = 7.58 × 10-8, OR = 0.75) showing consistent association with male sexual orientation. A fixed-effect meta-analysis including individuals of Han Chinese (n = 4791) and European ancestries (n = 408,995) revealed 3 genome-wide significant loci of same-sex sexual behavior (rs9677294, 2p22.1, SLC8A1, Pmeta = 1.95 × 10-8; rs2414487, 15q21.3, LOC145783, Pmeta = 4.53 × 10-9; rs2106525, 7q31.1, MDFIC, Pmeta = 6.24 × 10-9). These findings may provide new insights into the genetic basis of male sexual orientation from a wider population scope. Furthermore, we defined the average ZNF536-immunoreactivity (ZNF536-ir) concentration in the suprachiasmatic nucleus (SCN) as lower in homosexual individuals than in heterosexual individuals (0.011 ± 0.001 vs 0.021 ± 0.004, P = 0.013) in a postmortem study. In addition, compared with heterosexuals, the percentage of ZNF536 stained area in the SCN was also smaller in the homosexuals (0.075 ± 0.040 vs 0.137 ± 0.103, P = 0.043). More homosexual preference was observed in FMR1NB-knockout mice and we also found significant differences in the expression of serotonin, dopamine, and inflammation pathways that were reported to be related to sexual orientation when comparing CRISPR-mediated FMR1NB knockout mice to matched wild-type target C57 male mice.
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Affiliation(s)
- Shao-Hua Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
- National Human Brain Bank for Health and Disease, Hangzhou, Hangzhou, Zhejiang, China
- Brain Research Institute, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hai-Mei Li
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Hao Yu
- Department of Psychiatry, Jining Medical University, 133 Hehua Rd, Jining, Shandong, China
| | - Yan Liu
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Chen-Xing Liu
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xian-Bo Zuo
- Institute of Dermatology and Department of Dermatology at First Hospital, Anhui Medical University, Hefei, Anhui, China
| | - Jing Lu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Jia-Jun Jiang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Cai-Xi Xi
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Bo-Chao Huang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Hu-Ji Xu
- Department of General Office, Center for Disease Control of Jianggan District, Hangzhou, Zhejiang, China
| | - Jian-Bo Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Jian-Bo Lai
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Man-Li Huang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Jian-Ning Liu
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Dan-Ge Xu
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xi-Chao Guo
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Wei Wu
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xin Wu
- Department of Rheumatology and Immunology, Shanghai Changzheng Hospital, The Second Military Medial University, Shanghai, China
| | - Lei Jiang
- Department of Rheumatology and Immunology, Shanghai Changzheng Hospital, The Second Military Medial University, Shanghai, China
| | - Meng Li
- Department of Rheumatology and Immunology, Shanghai Changzheng Hospital, The Second Military Medial University, Shanghai, China
| | - Guang-Ping Zhang
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jin-Wen Huang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Ning Wei
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Wen Lv
- Department of Psychiatry, Seventh Hangzhou Hospital, Hangzhou, Zhejiang, China
| | - Jin-Feng Duan
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Hong-Li Qi
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Chan-Chan Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jing-Kai Chen
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Wei-Hua Zhou
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Wei-Juan Xu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China
| | - Chen-Feng Liu
- Medicines&Biochemical Products Branch, Zhejiang Medicine &Health Products I/E CO., Ltd, Hangzhou, Zhejiang, China
| | - Hai-Yong Liang
- BioMiao Biological Technology (Beijing) Co., Ltd, Beijing, China
| | - Jing Du
- Beijing Emei Tongde Technology Development Co., Ltd, Beijing, China
| | - Shu-Fa Zheng
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Qiao-Ling Lu
- Department of Aids Venereal Disease Control and Prevention, Shaoxing Center for Disease Control and Prevention, Shaoxing, Zhejiang, China
| | - Lin Zheng
- Department of Prevention and Treatment of AIDS and Sexually Transmitted Diseases, Center for Disease Control and Prevention of Xihu District, Hangzhou, Zhejiang, China
| | - Xiao-Wei Hu
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Feng-Xiang Chen
- Department of Clinical Laboratory, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Peng Chen
- International medical center, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Biao Zhu
- Department of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Li-Jun Xu
- Department of Infectious Disease, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Zhi-Min Ni
- Department of Disease Control, Center for Disease Control of Jianggan District, Hangzhou, Zhejiang, China
| | - Ye-Zhen Fang
- Department of Laboratory, Center for Disease Control of Jianggan District, Hangzhou, Zhejiang, China
| | - Zuo-Kai Yang
- Department of Aids Venereal Disease Control and Prevention, Shaoxing Center for Disease Control and Prevention, Shaoxing, Zhejiang, China
| | - Xin-Ren Shan
- Department of Aids Venereal Disease Control and Prevention, Shaoxing Center for Disease Control and Prevention, Shaoxing, Zhejiang, China
| | - En-de Zheng
- Beijing ViewSolid Biotechnology, Beijing, China
| | - Fan Zhang
- Shanghai OE Biotech. Co., Ltd, Beijing, China
| | | | - Yi Rao
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University School of Life Sciences, Beijing, China
| | - Dick Swaab
- Netherlands Institute for Neuroscience, Amsterdam, 1105 BA, The Netherlands
| | - Wei-Hua Yue
- Institute of Mental Health, National Clinical Research Center for Mental Disorders, Peking University Sixth Hospital, Beijing, China.
- NHC Key Laboratory of Mental Health, & Research Unit of Diagnosis and Treatment of Mood Cognitive Disorder (2018RU006), Chinese Academy of Medical Sciences, Beijing, China.
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.
| | - Yi Xu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
- The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, Zhejiang, China.
- National Human Brain Bank for Health and Disease, Hangzhou, Hangzhou, Zhejiang, China.
- Brain Research Institute, Zhejiang University, Hangzhou, Zhejiang, China.
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9
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Swaab DF, Wolff SEC, Bao AM. Sexual differentiation of the human hypothalamus: Relationship to gender identity and sexual orientation. Handb Clin Neurol 2021; 181:427-443. [PMID: 34238476 DOI: 10.1016/b978-0-12-820683-6.00031-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gender identity (an individual's perception of being male or female) and sexual orientation (heterosexuality, homosexuality, or bisexuality) are programmed into our brain during early development. During the intrauterine period in the second half of pregnancy, a testosterone surge masculinizes the fetal male brain. If such a testosterone surge does not occur, this will result in a feminine brain. As sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals, these two processes can be influenced independently of each other and can result in gender dysphoria. Nature produces a great variability for all aspects of sexual differentiation of the brain. Mechanisms involved in sexual differentiation of the brain include hormones, genetics, epigenetics, endocrine disruptors, immune response, and self-organization. Furthermore, structural and functional differences in the hypothalamus relating to gender dysphoria and sexual orientation are described in this review. All the genetic, postmortem, and in vivo scanning observations support the neurobiological theory about the origin of gender dysphoria, i.e., it is the sizes of brain structures, the neuron numbers, the molecular composition, functions, and connectivity of brain structures that determine our gender identity or sexual orientation. There is no evidence that one's postnatal social environment plays a crucial role in the development of gender identity or sexual orientation.
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Affiliation(s)
- Dick F Swaab
- Department Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Samantha E C Wolff
- Department Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Ai-Min Bao
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.
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10
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Wang Z, Hu JB, Ji GJ, Xu DR, Wang DD, Xi CX, Hu CC, Lu J, Du YL, Lu QQ, Huang TT, Lai JB, Chen JK, Zhou WH, Wei N, Xu Y, Wang K, Hu SH. Executive function and its relation to anatomical connectome in homosexual and heterosexual men. Quant Imaging Med Surg 2020; 10:1973-1983. [PMID: 33014729 DOI: 10.21037/qims-19-821b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Background Sexual orientation has been suggested to affect executive function, of which the neurobiological basis is still largely unknown. In this study, we explored the interrelationship between neuropsychological characteristics in homosexual and heterosexual men and their anatomical connectome by graph theoretical analysis. Methods Fifty-three homosexual and 47 heterosexual males underwent diffusion tensor magnetic resonance imaging (MRI) and neuropsychological assessments. Whole-brain anatomical networks were constructed using white matter tractography, performed on the diffusion tensor imaging data. Neuropsychological tests included the Wisconsin Card Sorting Test (WCST), the Continuous Performance Test (CPT) and the Trail-Making Test (TMT). Results The cognitive performance of homosexual men was significantly poorer than their heterosexual counterparts in terms of WCST total correct responses. Anatomical connectome analysis revealed a lower (P=0.001) anatomical connectivity between left PoCG and left SMG (P=0.003) in homosexual men as compared to heterosexual men. Linear regression analyses showed that the WCST total correct responses score was significantly linked with sexual orientation (P=0.001). The anatomical connectivity strength between left PoCG and left SMG was also shown to be significantly correlated with sexual orientation (P=0.039) and education (P=0.047). Conclusions Our study demonstrated the differences in the performance of WCST and anatomical connectome of large-scale brain networks between homosexual and heterosexual men, extending our understanding of the brain's circuitry and the characteristics of executive function in men of different sexual orientation.
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Affiliation(s)
- Zheng Wang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jian Bo Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Gong Jun Ji
- Laboratory of Cognitive Neuropsychology, Department of Medical Psychology, Anhui Medical University, Hefei, China
| | - Dong Rong Xu
- Epidemiology Division & MRI Unit, Department of Psychiatry, Columbia University & New York State Psychiatric Institute, New York, NY, USA
| | - Dan Dan Wang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Cai Xi Xi
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Chan Chan Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jing Lu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Yan Li Du
- Zhejiang University School of Medicine, Hangzhou, China
| | - Qiao Qiao Lu
- Zhejiang University School of Medicine, Hangzhou, China
| | | | - Jian Bo Lai
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jing Kai Chen
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Wei Hua Zhou
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Ning Wei
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Yi Xu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Kai Wang
- Laboratory of Cognitive Neuropsychology, Department of Medical Psychology, Anhui Medical University, Hefei, China
| | - Shao Hua Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
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11
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Abstract
Sex differences in brain and behavior of animals including humans result from an interaction between biological and environmental influences. This is also true for the differences between men and women concerning sexual orientation. Sexual differentiation is mediated by three groups of biological mechanisms: early actions of sex steroids, more direct actions of sex-specific genes not mediated by gonadal sex steroids and epigenetic mechanisms. Differential interactions with parents and conspecifics have additionally long-term influences on behavior. This presentation reviews available evidence indicating that these different mechanisms play a significant role in the control of sexual partner preference in animals and humans, in other words the homosexual versus heterosexual orientation. Clinical and epidemiological studies of phenotypically selected populations indicate that early actions of hormones and genetic factors clearly contribute to the determination of sexual orientation. The maternal embryonic environment also modifies the incidence of male homosexuality via immunological mechanisms. The relative contribution of each of these mechanisms remains however to be determined.
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12
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Wang Y, Wu H, Sun ZS. The biological basis of sexual orientation: How hormonal, genetic, and environmental factors influence to whom we are sexually attracted. Front Neuroendocrinol 2019; 55:100798. [PMID: 31593707 DOI: 10.1016/j.yfrne.2019.100798] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/29/2019] [Accepted: 10/03/2019] [Indexed: 12/11/2022]
Abstract
Humans develop relatively stable attractions to sexual partners during maturation and present a spectrum of sexual orientation from homosexuality to heterosexuality encompassing varying degrees of bisexuality, with some individuals also displaying asexuality. Sexual orientation represents a basic life phenomenon for humans. However, the molecular mechanisms underlying these diverse traits of sexual orientation remain highly controversial. In this review, we systematically discuss recent advancements in sexual orientation research, including those related to measurements and associated brain regions. Current findings regarding sexual orientation modulation by hormonal, genetic, maternal immune system, and environmental factors are summarized in both human and model systems. We also emphasize that future studies should recognize the differences between males and females and pay more attention to minor traits and the epigenetic regulation of sexual orientation. A comprehensive view of sexual orientation may promote our understanding of the biological basis of sex, and that of human reproduction, and evolution.
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Affiliation(s)
- Yan Wang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Haoda Wu
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of the Chinese Academy of Sciences, Beijing 100190, China
| | - Zhong Sheng Sun
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College, University of the Chinese Academy of Sciences, Beijing 100190, China; Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou 325000, China.
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13
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Affiliation(s)
- Melinda C. Mills
- Department of Sociology, University of Oxford, 42 Park End Street, Oxford, OX1 1JD, UK
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14
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Luoto S, Krams I, Rantala MJ. A Life History Approach to the Female Sexual Orientation Spectrum: Evolution, Development, Causal Mechanisms, and Health. Arch Sex Behav 2019; 48:1273-1308. [PMID: 30229521 DOI: 10.1007/s10508-018-1261-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 05/29/2018] [Accepted: 06/14/2018] [Indexed: 05/12/2023]
Abstract
Women's capacity for sexual fluidity is at least as interesting a phenomenon from the point of view of evolutionary biology and behavioral endocrinology as exclusively homosexual orientation. Evolutionary hypotheses for female nonheterosexuality have failed to fully account for the existence of these different categories of nonheterosexual women, while also overlooking broader data on the causal mechanisms, physiology, ontogeny, and phylogeny of female nonheterosexuality. We review the evolutionary-developmental origins of various phenotypes in the female sexual orientation spectrum using the synergistic approach of Tinbergen's four questions. We also present femme-specific and butch-specific hypotheses at proximate and ultimate levels of analysis. This review article indicates that various nonheterosexual female phenotypes emerge from and contribute to hormonally mediated fast life history strategies. Life history theory provides a biobehavioral explanatory framework for nonheterosexual women's masculinized body morphology, psychological dispositions, and their elevated likelihood of experiencing violence, substance use, obesity, teenage pregnancy, and lower general health. This pattern of life outcomes can create a feedback loop of environmental unpredictability and harshness which destabilizes intrauterine hormonal conditions in mothers, leading to a greater likelihood of fast life history strategies, global health problems, and nonheterosexual preferences in female offspring. We further explore the potential of female nonheterosexuality to function as an alloparental buffer that enables masculinizing alleles to execute their characteristic fast life history strategies as they appear in the female and the male phenotype. Synthesizing life history theory with the female sexual orientation spectrum enriches existing scientific knowledge on the evolutionary-developmental mechanisms of human sex differences.
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Affiliation(s)
- Severi Luoto
- English, Drama and Writing Studies, University of Auckland, Arts 1, Building 206, Room 616, 14A Symonds St., Auckland, 1010, New Zealand.
- School of Psychology, University of Auckland, Auckland, New Zealand.
| | - Indrikis Krams
- Department of Zoology and Animal Ecology, University of Latvia, Riga, Latvia
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Markus J Rantala
- Department of Biology & Turku Brain and Mind Center, University of Turku, Turku, Finland
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15
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Swift-Gallant A, Coome LA, Aitken M, Monks DA, VanderLaan DP. Evidence for distinct biodevelopmental influences on male sexual orientation. Proc Natl Acad Sci U S A 2019; 116:12787-92. [PMID: 31182568 DOI: 10.1073/pnas.1809920116] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Several biological mechanisms have been proposed to influence male sexual orientation, but the extent to which these mechanisms cooccur is unclear. Putative markers of biological processes are often used to evaluate the biological basis of male sexual orientation, including fraternal birth order, handedness, and familiality of same-sex sexual orientation; these biomarkers are proxies for immunological, endocrine, and genetic mechanisms. Here, we used latent profile analysis (LPA) to assess whether these biomarkers cluster within the same individuals or are present in different subgroups of nonheterosexual men. LPA defined four profiles of men based on these biomarkers: 1) A subgroup who did not have these biomarkers, 2) fraternal birth order, 3) handedness, and 4) familiality. While the majority of both heterosexual and nonheterosexual men were grouped in the profile that did not have any biomarker, the three profiles associated with a biomarker were composed primarily of nonheterosexual men. We then evaluated whether these subgroups differed on measures of gender nonconformity and personality that reliably show male sexual orientation differences. The subgroup without biomarkers was the most gender-conforming whereas the fraternal birth order subgroup was the most female-typical and agreeable, compared with the other profiles. Together, these findings suggest there are multiple distinct biodevelopmental pathways influencing same-sex sexual orientation in men.
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16
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Manzouri A, Savic I. Possible Neurobiological Underpinnings of Homosexuality and Gender Dysphoria. Cereb Cortex 2019; 29:2084-2101. [PMID: 30084980 PMCID: PMC6677918 DOI: 10.1093/cercor/bhy090] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/13/2018] [Accepted: 04/03/2018] [Indexed: 01/13/2023] Open
Abstract
Although frequently discussed in terms of sex dimorphism, the neurobiology of sexual orientation and identity is unknown. We report multimodal magnetic resonance imaging data, including cortical thickness (Cth), subcortical volumes, and resting state functional magnetic resonance imaging, from 27 transgender women (TrW), 40 transgender men (TrM), and 80 heterosexual (40 men) and 60 homosexual cisgender controls (30 men). These data show that whereas homosexuality is linked to cerebral sex dimorphism, gender dysphoria primarily involves cerebral networks mediating self-body perception. Among the homosexual cisgender controls, weaker sex dimorphism was found in white matter connections and a partly reversed sex dimorphism in Cth. Similar patterns were detected in transgender persons compared with heterosexual cisgender controls, but the significant clusters disappeared when adding homosexual controls, and correcting for sexual orientation. Instead, both TrW and TrM displayed singular features, showing greater Cth as well as weaker structural and functional connections in the anterior cingulate-precuneus and right occipito-parietal cortex, regions known to process own body perception in the context of self.
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Affiliation(s)
- A Manzouri
- Department of Women’s and Children’s Health, Karolinska Institute and University Hospital, Stockholm, Sweden
| | - I Savic
- Department of Women’s and Children’s Health, Karolinska Institute and University Hospital, Stockholm, Sweden
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA
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17
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Carosa E, Lenzi A, Jannini EA. Thyroid hormone receptors and ligands, tissue distribution and sexual behavior. Mol Cell Endocrinol 2018; 467:49-59. [PMID: 29175529 DOI: 10.1016/j.mce.2017.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/07/2017] [Accepted: 11/08/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Eleonora Carosa
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Andrea Lenzi
- Chair of Endocrinology, Department of Experimental Medicine, University of Rome Sapienza, Rome, Italy
| | - Emmanuele A Jannini
- Chair of Endocrinology & Medical Sexology (ENDOSEX), Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.
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18
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Fisher AD, Ristori J, Morelli G, Maggi M. The molecular mechanisms of sexual orientation and gender identity. Mol Cell Endocrinol 2018; 467:3-13. [PMID: 28847741 DOI: 10.1016/j.mce.2017.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 08/02/2017] [Accepted: 08/15/2017] [Indexed: 12/21/2022]
Abstract
Differences between males and females are widely represented in nature. There are gender differences in phenotypes, personality traits, behaviors and interests, cognitive performance, and proneness to specific diseases. The most marked difference in humans is represented by sexual orientation and core gender identity, the origins of which are still controversial and far from being understood. Debates continue on whether sexual behavior and gender identity are a result of biological (nature) or cultural (nurture) factors, with biology possibly playing a major role. The main goal of this review is to summarize the studies available to date on the biological factors involved in the development of both sexual orientation and gender identity. A systematic search of published evidence was performed using Medline (from January 1948 to June 2017). Review of the relevant literature was based on authors' expertise. Indeed, different studies have documented the possible role and interaction of neuroanatomic, hormonal and genetic factors. The sexual dimorphic brain is considered the anatomical substrate of psychosexual development, on which genes and gonadal hormones may have a shaping effect. In particular, growing evidence shows that prenatal and pubertal sex hormones permanently affect human behavior. In addition, heritability studies have demonstrated a role of genetic components. However, a convincing candidate gene has not been identified. Future studies (e.i. genome wide studies) are needed to better clarify the complex interaction between genes, anatomy and hormonal influences on psychosexual development.
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Affiliation(s)
- Alessandra D Fisher
- Department of Experimental, Clinical and Biomedical Sciences, Careggi University Hospital, Florence, Italy
| | - Jiska Ristori
- Department of Experimental, Clinical and Biomedical Sciences, Careggi University Hospital, Florence, Italy
| | - Girolamo Morelli
- Department of Surgical, Medical, Molecular and of the Critical Area Pathology, University of Pisa, Pisa, Italy
| | - Mario Maggi
- Department of Experimental, Clinical and Biomedical Sciences, Careggi University Hospital, Florence, Italy.
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19
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Abstract
The neurobiology of sexual orientation is frequently discussed in terms of cerebral sex dimorphism (defining both functional and structural sex differences). Yet, the information about possible cerebral differences between sex-matched homo and heterosexual persons is limited, particularly among women. In this multimodal MRI study, we addressed these issues by investigating possible cerebral differences between homo and heterosexual persons, and by asking whether there is any sex difference in this aspect. Measurements of cortical thickness (Cth), subcortical volumes, and functional and structural resting-state connections among 40 heterosexual males (HeM) and 40 heterosexual females (HeF) were compared with those of 30 homosexual males (HoM) and 30 homosexual females (HoF). Congruent with previous reports, sex differences were detected in heterosexual controls with regard to fractional anisotropy (FA), Cth, and several subcortical volumes. Homosexual groups did not display any sex differences in FA values. Furthermore, their functional connectivity was significantly less pronounced in the mesial prefrontal and precuneus regions. In these two particular regions, HoM also displayed thicker cerebral cortex than other groups, whereas HoF did not differ from HeF. In addition, in HoM the parietal Cth showed "sex-reversed" values, not observed in HoF. Homosexual orientation seems associated with a less pronounced sexual differentiation of white matter tracts and a less pronounced functional connectivity of the self-referential networks compared to heterosexual orientation. Analyses of Cth suggest that male and female homosexuality are not simple analogues of each other and that differences from heterosexual controls are more pronounced in HoM.
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Affiliation(s)
- Amirhossein Manzouri
- Department of Women's and Children's Health, and Neurology ClinicKarolinska Institutet and HospitalStickholmSE‐171 76Sweden
| | - Ivanka Savic
- Department of Women's and Children's Health, and Neurology ClinicKarolinska Institutet and HospitalStickholmSE‐171 76Sweden
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20
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Abstract
Though male homosexuality appears to be evolutionarily paradoxical, phenotypic feminization has been offered as a route for three current models positing a genetic basis for male homosexuality. We tested whether facial feminization is observable in gay men in two studies. In Study 1, using two composite images of gay and of heterosexual men, naive participants (N = 308) rated the "gay" face more highly on stereotypically feminine traits and actual femininity and the "heterosexual" face more highly on stereotypically masculine traits and actual masculinity. In Study 2, faciometrics of 428 Internet images of gay (N = 219) and heterosexual men were analyzed along six sexually dimorphic ratios. The faciometrics of gay men were more feminine, both in gestalt terms and for five of the six individual traits. The studies offer objective support for a more feminized facial phenotype in gay males that is difficult to explain through cultural or behavioral cues.
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Affiliation(s)
- Julia M Robertson
- a Department of Psychology , Buckinghamshire New University , Wycombe , Buckinghamshire , UK
| | - Barbara E Kingsley
- a Department of Psychology , Buckinghamshire New University , Wycombe , Buckinghamshire , UK
| | - Gina C Ford
- a Department of Psychology , Buckinghamshire New University , Wycombe , Buckinghamshire , UK
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21
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Gavrilets S, Friberg U, Rice WR. Understanding Homosexuality: Moving on from Patterns to Mechanisms. Arch Sex Behav 2018; 47:27-31. [PMID: 28986707 DOI: 10.1007/s10508-017-1092-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/26/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Sergey Gavrilets
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA.
- Department of Mathematics, University of Tennessee, Knoxville, TN, USA.
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, USA.
| | - Urban Friberg
- IFM Biology, Linkoping University, Linkoping, Sweden
| | - William R Rice
- Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA
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22
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Qin JB, Zhao GL, Wang F, Cai YM, Lan LN, Yang L, Feng TJ. Childhood Abuse Experiences and the COMT and MTHFR Genetic Variants Associated With Male Sexual Orientation in the Han Chinese Populations: A Case-Control Study. J Sex Med 2018; 15:29-42. [PMID: 29289372 DOI: 10.1016/j.jsxm.2017.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/16/2017] [Accepted: 11/20/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although it is widely acknowledged that genetic and environmental factors are involved in the development of male homosexuality, the causes are not fully understood. AIM To explore the association and interaction of childhood abuse experiences and genetic variants of the catechol-O-methyltransferase (COMT) and methylenetetrahydrofolate reductase (MTHFR) genes with the development of male homosexuality. METHODS A case-control study of 537 exclusively homosexual men and 583 exclusively heterosexual men was conducted, with data collected from March 2013 to August 2015. Data were analyzed using χ2 tests and logistic regression models. OUTCOMES Sociodemographic characteristics, childhood abuse experiences, and polymorphisms of COMT at rs4680, rs4818, and rs6267 and MTHFR at rs1801133. RESULTS More frequent occurrence of physical (adjusted odds ratio [aOR] = 1.78), emotional (aOR = 2.07), and sexual (aOR = 2.53) abuse during childhood was significantly associated with the development of male homosexuality. The polymorphisms of MTHFR at rs1801133 and COMT at rs4818 also were significantly associated with the development of male homosexuality in the homozygote comparisons (T/T vs C/C at rs1801133, aOR = 1.68; G/G vs C/C at rs4818, aOR = 1.75). In addition, significant interaction effects between childhood abuse experiences and the COMT and MTHFR genetic variants on the development of male homosexuality were found. CLINICAL TRANSLATION This is the first time that an association of childhood abuse, COMT and MTHFR genetic variants, and their interactions with development of male homosexuality was exhaustively explored, which could help provide new insight into the etiology of male homosexuality. STRENGTHS AND LIMITATIONS Because homosexual men are a relatively obscure population, it was impossible to select the study participants by random sampling, which could lead to selection bias. In addition, because this was a case-control study, recall bias was inevitable, and we could not verify causality. CONCLUSIONS Childhood abuse and the COMT and MTHFR genetic variants could be positively associated with the development of homosexuality. However, it remains unknown how these factors jointly play a role in the development of homosexuality, and more studies in different ethnic populations and with a larger sample and a prospective design are required to confirm our findings. Qin J-B, Zhao G-L, Wang F, et al. Childhood Abuse Experiences and the COMT and MTHFR Genetic Variants Associated With Male Sexual Orientation in the Han Chinese Populations: A Case-Control Study. J Sex Med 2018;15:29-42.
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Affiliation(s)
- Jia-Bi Qin
- Department of Epidemiology and Health Statistics, School of Public Health, Central South University, Changsha, Hunan, China
| | - Guang-Lu Zhao
- Shenzhen Center for Chronic Disease Control, Shenzhen, China
| | - Feng Wang
- Shenzhen Center for Chronic Disease Control, Shenzhen, China
| | - Yu-Mao Cai
- Shenzhen Center for Chronic Disease Control, Shenzhen, China
| | - Li-Na Lan
- Shenzhen Center for Chronic Disease Control, Shenzhen, China
| | - Lin Yang
- Department of Epidemiology and Health Statistics, School of Public Health, Central South University, Changsha, Hunan, China
| | - Tie-Jian Feng
- Shenzhen Center for Chronic Disease Control, Shenzhen, China.
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Sanders AR, Beecham GW, Guo S, Dawood K, Rieger G, Badner JA, Gershon ES, Krishnappa RS, Kolundzija AB, Duan J, Gejman PV, Bailey JM, Martin ER. Genome-Wide Association Study of Male Sexual Orientation. Sci Rep 2017; 7:16950. [PMID: 29217827 PMCID: PMC5721098 DOI: 10.1038/s41598-017-15736-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/31/2017] [Indexed: 11/11/2022] Open
Abstract
Family and twin studies suggest that genes play a role in male sexual orientation. We conducted a genome-wide association study (GWAS) of male sexual orientation on a primarily European ancestry sample of 1,077 homosexual men and 1,231 heterosexual men using Affymetrix single nucleotide polymorphism (SNP) arrays. We identified several SNPs with p < 10-5, including regions of multiple supporting SNPs on chromosomes 13 (minimum p = 7.5 × 10-7) and 14 (p = 4.7 × 10-7). The genes nearest to these peaks have functions plausibly relevant to the development of sexual orientation. On chromosome 13, SLITRK6 is a neurodevelopmental gene mostly expressed in the diencephalon, which contains a region previously reported as differing in size in men by sexual orientation. On chromosome 14, TSHR genetic variants in intron 1 could conceivably help explain past findings relating familial atypical thyroid function and male homosexuality. Furthermore, skewed X chromosome inactivation has been found in the thyroid condition, Graves' disease, as well as in mothers of homosexual men. On pericentromeric chromosome 8 within our previously reported linkage peak, we found support (p = 4.1 × 10-3) for a SNP association previously reported (rs77013977, p = 7.1 × 10-8), with the combined analysis yielding p = 6.7 × 10-9, i.e., a genome-wide significant association.
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Affiliation(s)
- Alan R Sanders
- Department of Psychiatry and Behavioral Sciences, NorthShore University HealthSystem Research Institute, Evanston, Illinois, 60201, United States of America.
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, Illinois, 60637, United States of America.
| | - Gary W Beecham
- Department of Human Genetics, University of Miami, Miami, Florida, 33136, United States of America
| | - Shengru Guo
- Department of Human Genetics, University of Miami, Miami, Florida, 33136, United States of America
| | - Khytam Dawood
- Department of Psychology, Pennsylvania State University, University Park, Pennsylvania, 16802, United States of America
| | - Gerulf Rieger
- Department of Psychology, University of Essex, Colchester, England, CO4 3SQ, United Kingdom
| | - Judith A Badner
- Department of Psychiatry, Rush University Medical Center, Chicago, Illinois, 60612, United States of America
| | - Elliot S Gershon
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, Illinois, 60637, United States of America
| | - Ritesha S Krishnappa
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, Elmhurst, New York, 11373, United States of America
| | - Alana B Kolundzija
- Department of Sociomedical Sciences, Mailman School of Public Health, Columbia University, New York, New York, 10027, United States of America
| | - Jubao Duan
- Department of Psychiatry and Behavioral Sciences, NorthShore University HealthSystem Research Institute, Evanston, Illinois, 60201, United States of America
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, Illinois, 60637, United States of America
| | - Pablo V Gejman
- Department of Psychiatry and Behavioral Sciences, NorthShore University HealthSystem Research Institute, Evanston, Illinois, 60201, United States of America
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, Illinois, 60637, United States of America
| | - J Michael Bailey
- Department of Psychology, Northwestern University, Evanston, Illinois, 60208, United States of America
| | - Eden R Martin
- Department of Human Genetics, University of Miami, Miami, Florida, 33136, United States of America
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Camperio Ciani A, Battaglia U, Cesare L, Camperio Ciani G, Capiluppi C. Possible Balancing Selection in Human Female Homosexuality. Hum Nat 2017; 29:14-32. [DOI: 10.1007/s12110-017-9309-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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VanderLaan DP, Petterson LJ, Vasey PL. Elevated Kin-Directed Altruism Emerges in Childhood and Is Linked to Feminine Gender Expression in Samoan Fa'afafine: A Retrospective Study. Arch Sex Behav 2017; 46:95-108. [PMID: 27987088 DOI: 10.1007/s10508-016-0884-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 10/15/2016] [Accepted: 10/17/2016] [Indexed: 06/06/2023]
Abstract
Androphilia refers to sexual attraction toward adult males, whereas gynephilia refers to sexual attraction toward adult females. The kin selection hypothesis posits that androphilic males help kin increase their reproductive output via kin-directed altruism, thus offsetting their own lowered reproduction and contributing to the fitness of genes underpinning male androphilia. Support for this hypothesis has been garnered in several Samoan studies showing that feminine androphilic males (known locally as fa'afafine) report elevated willingness to invest in nieces and nephews in adulthood. Also, recalled childhood kin attachment and concern for kin's well-being are elevated among Canadian androphilic males (i.e., gay men) and positively associated with childhood feminine gender expression. This study examined whether these childhood patterns were cross-culturally consistent and associated with adulthood kin-directed altruism in a Samoan sample. Samoan gynephilic men, androphilic women, and fa'afafine (N = 470) completed measures of recalled childhood kin attachment and concern for the well-being of kin, recalled childhood gender expression, and willingness in adulthood to invest in nieces and nephews. Fa'afafine recalled elevated anxiety due to separation from kin relative to men and elevated concern for kin's well-being relative to both men and women. Within groups, these characteristics were most robustly associated with childhood feminine gender expression and willingness in adulthood to invest in nieces and nephews among fa'afafine. These findings are consistent with the kin selection hypothesis and the adaptive feminine phenotype model, which proposes that a disposition toward elevated kin-directed altruism among androphilic males is associated with feminine gender expression.
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Affiliation(s)
- Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, Deerfield Hall, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada.
- Underserved Populations Research Program, Child, Youth and Family Division, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | - Lanna J Petterson
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
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Semenyna SW, Petterson LJ, VanderLaan DP, Vasey PL. A Comparison of the Reproductive Output Among the Relatives of Samoan Androphilic Fa'afafine and Gynephilic Men. Arch Sex Behav 2017; 46:87-93. [PMID: 27785648 DOI: 10.1007/s10508-016-0765-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 04/22/2016] [Accepted: 04/26/2016] [Indexed: 06/06/2023]
Abstract
The sexually antagonistic gene hypothesis (SAGH) for male androphilia posits that genes associated with androphilia (i.e., sexual attraction to adult males) will result in lowered reproduction when present in males, but increased reproduction when present in females. Findings derived from some Western European samples furnish support for the SAGH; however, results from studies conducted in other regions of the world have been more equivocal. Our previous research in Samoa indicated that the mothers as well as the maternal and paternal grandmothers of androphilic males (known locally as fa'afafine) exhibit elevated reproductive output when compared to the relatives of gynephilic men (i.e., males that are sexually attracted to adult females). The present replication study tested the SAGH in Samoa using a sample that was 122 % larger than the one previously studied by our group (VanderLaan, Forrester, Petterson, & Vasey, 2012). In line with the predictions of the SAGH, we hypothesized that the grandmothers, aunts, and mothers of fa'afafine would show elevated reproductive output compared to those of Samoan gynephilic men. Data were collected from 191 fa'afafine and 191 gynephilic men on the reproductive output of their paternal and maternal biological relatives (i.e., mothers, grandmothers, aunts, uncles). The mothers and maternal grandmothers of fa'afafine showed elevated reproductive output compared to those of gynephilic men. The paternal grandmother effect was not replicated. Although these results are consistent with the SAGH, a lack of difference in the reproductive output of aunts renders support for the SAGH in Samoa equivocal.
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Affiliation(s)
- Scott W Semenyna
- Department of Psychology, University of Lethbridge, C866 University Hall, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada.
| | - Lanna J Petterson
- Department of Psychology, University of Lethbridge, C866 University Hall, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
| | - Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
- Underserved Populations Research Program, Child, Youth and Family Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, C866 University Hall, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada
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Griffiths DA. Queer Genes: Realism, Sexuality and Science. J Crit Realism 2016; 15:511-529. [PMID: 28058037 PMCID: PMC5167250 DOI: 10.1080/14767430.2016.1210872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
What are 'gay genes' and are they real? This article looks at key research into these hypothesized gay genes, made possible, in part, by the Human Genome Project. I argue that the complexity of both genetics and human sexuality demands a truly critical approach: one that takes into account feminist epistemologies of science and queer approaches to the body, while putting into conversation resources from agential realism and critical realism. This approach is able to maintain the agential complexity of genetic materiality, while also critically challenging the seemingly stable relationships between sex, gender and sexuality.
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Abstract
In the 1990s the discovery of a ‘gay gene’ was widely reported in the news media, often as front-page stories. Focusing on the print media presentation of Dean Hamer’s 1993 and 1995 scientific papers reporting finding a genetic marker for homosexuality, we examine how these studies were framed in a selected sample of US and British newspapers and news magazines. We found disparate constructions of the ‘gay gene’ in each press culture. The US press reported Hamer’s study as good science and treated it with ‘cautious optimism’ while the British press reported the research as ‘the perils of the gay gene.’ We discuss how these studies received such widespread attention and the sources and implications of the variant images of the ‘gay gene’ in the news.
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Affiliation(s)
- Dean Hamer
- Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
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Abstract
Researchers have documented substantial variability in the development and expression of same-sex sexuality, especially among women, posing challenges to traditional linear developmental models. In this article, I argue for a new approach to conceptualizing the development and expression of female same-sex sexuality over the life course, based in dynamical systems theory. Dynamical systems models seek to explain how complex patterns emerge, stabilize, change, and restabilize over time. Although originally developed by mathematicians and physicists to model complex physical phenomena in the natural world, they have increasingly been applied to social-behavioral phenomena, ranging from motor development to cognition to language. I demonstrate the utility of this approach for modeling change over time in female same-sex sexuality, reviewing extant published research and also introducing data collected from an ongoing, 10-year longitudinal study of young nonheterosexual women. I provide evidence that female same-sex sexuality demonstrates the emblematic features of a dynamical system: nonlinear change over time, spontaneous emergence of novel forms, and periodic reorganizations and phase transitions within the overall system. I highlight the specific contribution of a dynamical systems perspective for understanding such phenomena and suggest directions for future study.
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Abstract
Summary Ongoing political controversies around the world exemplify a long-standing and widespread preoccupation with the acceptability of homosexuality. Nonheterosexual people have seen dramatic surges both in their rights and in positive public opinion in many Western countries. In contrast, in much of Africa, the Middle East, the Caribbean, Oceania, and parts of Asia, homosexual behavior remains illegal and severely punishable, with some countries retaining the death penalty for it. Political controversies about sexual orientation have often overlapped with scientific controversies. That is, participants on both sides of the sociopolitical debates have tended to believe that scientific findings—and scientific truths—about sexual orientation matter a great deal in making political decisions. The most contentious scientific issues have concerned the causes of sexual orientation—that is, why are some people heterosexual, others bisexual, and others homosexual? The actual relevance of these issues to social, political, and ethical decisions is often poorly justified, however.
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Affiliation(s)
| | | | | | | | - Eric Vilain
- Department of Human Genetics, University of California, Los Angeles
- Department of Pediatrics, University of California, Los Angeles
- Department of Urology, University of California, Los Angeles
- Joint International Unit on Epigenetics, Data, and Politics, Centre National de la Recherche Scientifique, Paris, France
| | - Marc Epprecht
- Department of History, Queen’s University
- Department of Global Development Studies, Queen’s University
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VanderLaan DP, Petterson LJ, Vasey PL. Femininity and Kin-Directed Altruism in Androphilic Men: A Test of an Evolutionary Developmental Model. Arch Sex Behav 2016; 45:619-633. [PMID: 26597647 DOI: 10.1007/s10508-015-0632-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 07/15/2015] [Accepted: 09/16/2015] [Indexed: 06/05/2023]
Abstract
Androphilia refers to sexual attraction and arousal toward males whereas gynephilia refers to sexual attraction and arousal toward females. This study tested the adaptive feminine phenotype model of the evolution of male androphilia via kin selection, which posits that the development of an evolved disposition toward elevated kin-directed altruism among androphilic males is contingent on the behavioral expression of femininity. Gynephilic men, androphilic women, and androphilic men (N = 387) completed measures of childhood and adulthood gender expression and concern for kin's well-being. Adulthood femininity correlated positively with uncle/aunt-like tendencies among androphilic men and women. Although androphilic women reported greater willingness to invest in nieces and nephews than gynephilic and androphilic men, mediation analyses indicated that adult femininity completely mediated these group differences. In addition, changes in the expression of femininity between childhood and adulthood were associated with parallel changes in concern for the well-being of kin among androphilic men. Thus, these findings suggest that femininity is key to the expression of kin-directed altruism among androphilic males and may have been important in the evolution of male androphilia.
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Affiliation(s)
- Doug P VanderLaan
- Department of Psychology, University of Toronto-Mississauga, Deerfield Hall, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada.
- Underserved Populations Research Program, Child, Youth and Family Division, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | - Lanna J Petterson
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
| | - Paul L Vasey
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
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Yu W, Tu D, Hong F, Wang J, Liu X, Cai Y, Xu R, Zhao G, Wang F, Pan H, Wu S, Feng T, Wang B. Analysis of the Association between Catechol‐O‐Methyltransferase Val158Met and Male Sexual Orientation. J Sex Med 2015; 12:1920-6. [DOI: 10.1111/jsm.12978] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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VanderLaan DP, Petterson LJ, Vasey PL. Elevated childhood separation anxiety: An early developmental expression of heightened concern for kin in homosexual men? Personality and Individual Differences 2015. [DOI: 10.1016/j.paid.2014.03.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sanders AR, Martin ER, Beecham GW, Guo S, Dawood K, Rieger G, Badner JA, Gershon ES, Krishnappa RS, Kolundzija AB, Duan J, Gejman PV, Bailey JM. Genome-wide scan demonstrates significant linkage for male sexual orientation. Psychol Med 2015; 45:1379-1388. [PMID: 25399360 DOI: 10.1017/s0033291714002451] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Findings from family and twin studies support a genetic contribution to the development of sexual orientation in men. However, previous studies have yielded conflicting evidence for linkage to chromosome Xq28. METHOD We conducted a genome-wide linkage scan on 409 independent pairs of homosexual brothers (908 analyzed individuals in 384 families), by far the largest study of its kind to date. RESULTS We identified two regions of linkage: the pericentromeric region on chromosome 8 (maximum two-point LOD = 4.08, maximum multipoint LOD = 2.59), which overlaps with the second strongest region from a previous separate linkage scan of 155 brother pairs; and Xq28 (maximum two-point LOD = 2.99, maximum multipoint LOD = 2.76), which was also implicated in prior research. CONCLUSIONS Results, especially in the context of past studies, support the existence of genes on pericentromeric chromosome 8 and chromosome Xq28 influencing development of male sexual orientation.
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Affiliation(s)
- A R Sanders
- Department of Psychiatry and Behavioral Sciences,NorthShore University HealthSystem Research Institute,Evanston,IL,USA
| | - E R Martin
- Department of Human Genetics,University of Miami,Miami,FL,USA
| | - G W Beecham
- Department of Human Genetics,University of Miami,Miami,FL,USA
| | - S Guo
- Department of Human Genetics,University of Miami,Miami,FL,USA
| | - K Dawood
- Department of Psychology,Pennsylvania State University,University Park,PA,USA
| | - G Rieger
- Department of Psychology,University of Essex,Colchester,England,UK
| | - J A Badner
- Department of Psychiatry and Behavioral Neuroscience,University of Chicago,Chicago,IL,USA
| | - E S Gershon
- Department of Psychiatry and Behavioral Neuroscience,University of Chicago,Chicago,IL,USA
| | - R S Krishnappa
- Department of Psychiatry,Icahn School of Medicine at Mount Sinai,Elmhurst,NY,USA
| | - A B Kolundzija
- Department of Sociomedical Sciences,Mailman School of Public Health, Columbia University,New York,NY,USA
| | - J Duan
- Department of Psychiatry and Behavioral Sciences,NorthShore University HealthSystem Research Institute,Evanston,IL,USA
| | - P V Gejman
- Department of Psychiatry and Behavioral Sciences,NorthShore University HealthSystem Research Institute,Evanston,IL,USA
| | - J M Bailey
- Department of Psychology,Northwestern University,Evanston,IL,USA
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38
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Abstract
Sexual conflict likely plays a crucial role in the origin and maintenance of homosexuality in our species. Although environmental factors are known to affect human homosexual (HS) preference, sibling concordances and population patterns related to HS indicate that genetic components are also influencing this trait in humans. We argue that multilocus, partially X-linked genetic factors undergoing sexually antagonistic selection that promote maternal female fecundity at the cost of occasional male offspring homosexuality are the best candidates capable of explaining the frequency, familial clustering, and pedigree asymmetries observed in HS male proband families. This establishes male HS as a paradigmatic example of sexual conflict in human biology. HS in females, on the other hand, is currently a more elusive phenomenon from both the empirical and theoretical standpoints because of its fluidity and marked environmental influence. Genetic and epigenetic mechanisms, the latter involving sexually antagonistic components, have been hypothesized for the propagation and maintenance of female HS in the population. However, further data are needed to truly clarify the evolutionary dynamics of this trait.
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Affiliation(s)
- Andrea Camperio Ciani
- Dipartimento di Filosofia, Sociologia, Pedagogia e Psicologia Applicata, Università di Padova, 35100 Padova, Italy
| | - Umberto Battaglia
- Dipartimento di Filosofia, Sociologia, Pedagogia e Psicologia Applicata, Università di Padova, 35100 Padova, Italy
| | - Giovanni Zanzotto
- Dipartimento di Psicologia Generale, Università di Padova, 35100 Padova, Italy
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Olvera-Hernández S, Fernández-Guasti A. Perinatal administration of aromatase inhibitors in rodents as animal models of human male homosexuality: similarities and differences. Adv Neurobiol 2015; 10:381-406. [PMID: 25287550 DOI: 10.1007/978-1-4939-1372-5_18] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this chapter we briefly review the evidence supporting the existence of biological influences on sexual orientation. We focus on basic research studies that have affected the estrogen synthesis during the critical periods of brain sexual differentiation in male rat offspring with the use of aromatase inhibitors, such as 1,4,6-androstatriene-3,17 (ATD) and letrozole. The results after prenatal and/or postnatal treatment with ATD reveal that these animals, when adults, show female sexual responses, such as lordosis or proceptive behaviors, but retain their ability to display male sexual activity with a receptive female. Interestingly, the preference and sexual behavior of these rats vary depending upon the circadian rhythm.Recently, we have established that the treatment with low doses of letrozole during the second half of pregnancy produces male rat offspring, that when adults spend more time in the company of a sexually active male than with a receptive female in a preference test. In addition, they display female sexual behavior when forced to interact with a sexually experienced male and some typical male sexual behavior when faced with a sexually receptive female. Interestingly, these males displayed both sexual behavior patterns spontaneously, i.e., in absence of exogenous steroid hormone treatment. Most of these features correspond with those found in human male homosexuals; however, the "bisexual" behavior shown by the letrozole-treated rats may be related to a particular human population. All these data, taken together, permit to propose letrozole prenatal treatment as a suitable animal model to study human male homosexuality and reinforce the hypothesis that human sexual orientation is underlied by changes in the endocrine milieu during early development.
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Affiliation(s)
- Sandra Olvera-Hernández
- Department of Pharmacobiology, Center for Research and Advanced Studies (CINVESTAV), Calzada de los Tenorios 235 Colonia Granjas Coapa, 14330, México, D.F., Mexico,
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Dehlin JP, Galliher RV, Bradshaw WS, Crowell KA. Psychosocial Correlates of Religious Approaches to Same-Sex Attraction: A Mormon Perspective. Journal of Gay & Lesbian Mental Health 2014. [DOI: 10.1080/19359705.2014.912970] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Brakefield TA, Mednick SC, Wilson HW, De Neve JE, Christakis NA, Fowler JH. Same-sex sexual attraction does not spread in adolescent social networks. Arch Sex Behav 2014; 43:335-44. [PMID: 23842784 PMCID: PMC3888648 DOI: 10.1007/s10508-013-0142-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 03/07/2013] [Accepted: 05/10/2013] [Indexed: 06/02/2023]
Abstract
Peers have a powerful effect on adolescents' beliefs, attitudes, and behaviors. Here, we examine the role of social networks in the spread of attitudes towards sexuality using data from the National Longitudinal Study of Adolescent Health (Add Health). Although we found evidence that both sexual activity (OR = 1.79) and desire to have a romantic relationship (OR = 2.69) may spread from person to person, attraction to same sex partners did not spread (OR = 0.96). Analyses of comparable power to those that suggest positive and significant peer-to-peer influence in sexual behavior fail to demonstrate a significant relationship on sexual attraction between friends or siblings. These results suggest that peer influence has little or no effect on the tendency toward heterosexual or homosexual attraction in teens, and that sexual orientation is not transmitted via social networks.
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Affiliation(s)
- Tiffany A Brakefield
- Department of Psychology, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA,
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42
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Abstract
Sexual orientation is one of the largest sex differences in humans. The vast majority of the population is heterosexual, that is, they are attracted to members of the opposite sex. However, a small but significant proportion of people are bisexual or homosexual and experience attraction to members of the same sex. The origins of the phenomenon have long been the subject of scientific study. In this chapter, we will review the evidence that sexual orientation has biological underpinnings and consider the involvement of epigenetic mechanisms. We will first discuss studies that show that sexual orientation has a genetic component. These studies show that sexual orientation is more concordant in monozygotic twins than in dizygotic ones and that male sexual orientation is linked to several regions of the genome. We will then highlight findings that suggest a link between sexual orientation and epigenetic mechanisms. In particular, we will consider the case of women with congenital adrenal hyperplasia (CAH). These women were exposed to high levels of testosterone in utero and have much higher rates of nonheterosexual orientation compared to non-CAH women. Studies in animal models strongly suggest that the long-term effects of hormonal exposure (such as those experienced by CAH women) are mediated by epigenetic mechanisms. We conclude by describing a hypothetical framework that unifies genetic and epigenetic explanations of sexual orientation and the continued challenges facing sexual orientation research.
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Abstract
A role for serotonin in male sexual preference was recently uncovered by our finding that male mutant mice lacking serotonin have lost sexual preference. Here we show that female mouse mutants lacking either central serotonergic neurons or serotonin prefer female over male genital odors when given a choice, and displayed increased female-female mounting when presented either with a choice of a male and a female target or only with a female target. Pharmacological manipulations and genetic rescue experiments showed that serotonin is required in adults. Behavioral changes caused by deficient serotonergic signaling were not due to changes in plasma concentrations of sex hormones. We demonstrate that a genetic manipulation reverses sexual preference without involving sex hormones. Our results indicate that serotonin controls sexual preference.
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Vanderlaan DP, Forrester DL, Petterson LJ, Vasey PL. The prevalence of fa'afafine relatives among Samoan gynephilic men and fa'afafine. Arch Sex Behav 2013; 42:353-359. [PMID: 23054259 DOI: 10.1007/s10508-012-0015-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 07/21/2012] [Accepted: 08/04/2012] [Indexed: 06/01/2023]
Abstract
Androphilia refers to sexual attraction to adult males whereas gynephilia refers to sexual attraction to adult females. In Western populations, androphilia in males is familial, but the precise nature of this phenomenon is unclear. Some studies show that androphilic males have preponderances of androphilic male relatives in the maternal, but not paternal, line. In contrast, other studies show that male androphilia clusters in both the maternal and paternal lines. Low fertility populations are susceptible to producing anomalous patterns with respect to biodemographic correlates of male sexual orientation, which may account for discrepancies in the familial patterning of male androphilia across Western studies. We focused on a high fertility population to determine which pattern, if any, prevailed. The prevalence of androphilic male relatives was compared for Samoan gynephilic and androphilic male probands. Samoan androphilic males are known locally as fa'afafine. Compared to Samoan gynephilic males, fa'afafine had significantly more fa'afafine relatives in their maternal and paternal lines. The prevalence of fa'afafine relatives was not significantly different between the paternal and maternal lines for fa'afafine or gynephilic male probands. These findings indicate that male androphilia is familial in Samoa and that it clusters in both the paternal and maternal lines in high fertility populations. We consider our findings in the context of possible explanations for the familial clustering of male androphilia. In addition, we detail how the data presented here illuminate the prevalence of male androphilia in the Samoan population.
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Affiliation(s)
- Doug P Vanderlaan
- Department of Psychology, University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada.
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Camperio Ciani A, Pellizzari E. Fecundity of paternal and maternal non-parental female relatives of homosexual and heterosexual men. PLoS One 2012; 7:e51088. [PMID: 23227237 PMCID: PMC3515521 DOI: 10.1371/journal.pone.0051088] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 10/31/2012] [Indexed: 11/25/2022] Open
Abstract
A variety of social, developmental, biological and genetic factors influence sexual orientation in males. Thus, several hypotheses have attempted to explain the sustenance of genetic factors that influence male homosexuality, despite decreased fecundity within the homosexuals. Kin selection, the existence of maternal effects and two forms of balancing selection, sexually antagonistic selection and overdominance, have been proposed as compensatory mechanisms for reduced homosexual fecundity. Here, we suggest that the empirical support for kin selection and maternal effects cannot account for the low universal frequency and stability of the distribution of homosexuals. To identify the responsible compensatory mechanism, we analyzed fecundity in 2,100 European female relatives, i.e., aunts and grandmothers, of either homosexual or heterosexual probands who were matched in terms of age, culture and sampling strategy. Female relatives were chosen to avoid the sampling bias of the fraternal birth order effect, which occurs when indirectly sampling mothers though their homosexual sons. We observed that the maternal aunts and grandmothers of homosexual probands were significantly more fecund compared with the maternal aunts and maternal grandmothers of the heterosexual probands. No difference in fecundity was observed in the paternal female lines (grandmothers or aunts) from either of the two proband groups. Moreover, due to the selective increase in maternal female fecundity, the total female fecundity was significantly higher in homosexual than heterosexual probands, thus compensating for the reduced fecundity of homosexuals. Altogether, these data support an X-linked multi-locus sexually antagonistic hypothesis rather than an autosomal multi-locus overdominance hypothesis.
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Lawall FAA, Trivellato IO, Shikasho L, Filgueiras MST, Silva NCD, Almeida TRD. Heranças familiares: entre os genes e os afetos. Saude soc 2012. [DOI: 10.1590/s0104-12902012000200018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sabe-se que o câncer de mama é uma patologia que afeta um número considerável de mulheres e levanta diversos questionamentos entre os profissionais da saúde. A história familiar é considerada um fator de risco e os profissionais das diversas áreas da saúde apontam-na como fator decisivo na determinação de aspectos relativos ao processo de adoecimento. Entretanto, a história familiar é abordada de maneiras distintas pelos diferentes profissionais, de acordo com o enfoque tomado. O presente artigo propõe uma leitura global da história familiar considerando as diversas "heranças" que atravessam e constituem o sujeito. A partir da análise de instrumentos como o heredograma e o genograma, observa-se que, enquanto o saber médico se ocupa de uma história familiar que está previamente determinada por fatores genéticos e, portanto, pouco acessível à intervenções preventivas, o saber psicológico busca o que há de particular na história familiar do sujeito e na maneira como este se insere na trama das relações que compõem essa história. Desse modo, abre-se a possibilidade de re-significar essa história e de encontrar uma outra via que não a do adoecer. Propicia-se, a partir daí, um espaço de discussão onde saberes e práticas interdisciplinares possam se complementar na perspectiva de uma integralidade na prevenção e promoção da saúde.
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Affiliation(s)
| | | | - Larissa Shikasho
- UFJF; Núcleo Interdisciplinar de Investigação Psicossomática, Brasil
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47
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Abstract
Research has shown that people are able to judge sexual orientation from faces with above-chance accuracy, but little is known about how these judgments are formed. Here, we investigated the importance of well-established face processing mechanisms in such judgments: featural processing (e.g., an eye) and configural processing (e.g., spatial distance between eyes). Participants judged sexual orientation from faces presented for 50 milliseconds either upright, which recruits both configural and featural processing, or upside-down, when configural processing is strongly impaired and featural processing remains relatively intact. Although participants judged women's and men's sexual orientation with above-chance accuracy for upright faces and for upside-down faces, accuracy for upside-down faces was significantly reduced. The reduced judgment accuracy for upside-down faces indicates that configural face processing significantly contributes to accurate snap judgments of sexual orientation.
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Affiliation(s)
- Joshua A Tabak
- Department of Psychology, University of Washington, Seattle, Washington, United States of America.
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48
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VanderLaan DP, Forrester DL, Petterson LJ, Vasey PL. Offspring production among the extended relatives of Samoan men and fa'afafine. PLoS One 2012; 7:e36088. [PMID: 22558342 PMCID: PMC3338633 DOI: 10.1371/journal.pone.0036088] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 03/30/2012] [Indexed: 11/19/2022] Open
Abstract
Androphilia refers to sexual attraction to adult males, whereas gynephilia refers to sexual attraction to adult females. Male androphilia is an evolutionary paradox. Its development is at least partially influenced by genetic factors, yet male androphiles exhibit lower reproductive output, thus raising the question of how genetic factors underlying its development persist. The sexual antagonism hypothesis posits that the fitness costs associated with genetic factors underlying male androphilia are offset because these same factors lead to elevated reproduction on the part of the female relatives of androphilic males. Western samples drawn from low fertility populations have yielded inconsistent results when testing this hypothesis. Some studies documented elevated reproduction among the matrilineal female kin of androphilic males, whereas others found such effects in the paternal line. Samoa is a high-fertility population in which individuals reproduce closer to their maximum capacities. This study compared the reproductive output of the paternal and maternal line grandmothers, aunts, and uncles of 86 Samoan androphilic males, known locally as fa'afafine, and 86 Samoan gynephilic males. Reproductive output was elevated in the paternal and maternal line grandmothers, but not aunts or uncles, of fa'afafine. These findings are consistent with the sexual antagonism hypothesis and suggest that male androphilia is associated with elevated reproduction among extended relatives in both the maternal and paternal line. Discussion focuses on how this study, in conjunction with the broader literature, informs various models for the evolution of male androphilia via elevated reproduction on the part of female kin.
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Affiliation(s)
- Doug P VanderLaan
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada.
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49
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Abstract
The gay gene was first identified in 1993 as a correlation between the genetic marker Xq28 and gay male sexuality. The results of this original study were never replicated, and the biological reality of such an entity remains hypothetical. However, despite such tenuous provenance, the gay gene has persisted as a reference in science news, popular science writings, and in press releases and editorials about biomedical research. An examination of the life of the gay gene in U.K. news media demonstrates that the gay gene has become an assumed back-story to genetic sexuality research over time, and that the critique of its very existence has been diminished. Latterly, the gay gene has entered into the online biomedical databases of the 21st century with the same pattern of persistence and diminishing critique. This article draws on an analysis of the U.K. press and online databases to represent the process through which the address of the gay gene has shifted and become an index of biomedicalization. The consequent unmooring of the gay gene from accountability and accuracy demonstrates that the organization of biomedical databases could benefit from greater cross-disciplinary attention.
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Affiliation(s)
- Kate O'Riordan
- Department of Media, Film, and Music, University of Sussex, Falmer BN19RG, England.
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50
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Abstract
Many people believe that sexual orientation (homosexuality vs. heterosexuality) is determined by education and social constraints. There are, however, a large number of studies indicating that prenatal factors have an important influence on this critical feature of human sexuality. Sexual orientation is a sexually differentiated trait (over 90% of men are attracted to women and vice versa). In animals and men, many sexually differentiated characteristics are organized during early life by sex steroids, and one can wonder whether the same mechanism also affects human sexual orientation. Two types of evidence support this notion. First, multiple sexually differentiated behavioral, physiological, or even morphological traits are significantly different in homosexual and heterosexual populations. Because some of these traits are known to be organized by prenatal steroids, including testosterone, these differences suggest that homosexual subjects were, on average, exposed to atypical endocrine conditions during development. Second, clinical conditions associated with significant endocrine changes during embryonic life often result in an increased incidence of homosexuality. It seems therefore that the prenatal endocrine environment has a significant influence on human sexual orientation but a large fraction of the variance in this behavioral characteristic remains unexplained to date. Genetic differences affecting behavior either in a direct manner or by changing embryonic hormone secretion or action may also be involved. How these biological prenatal factors interact with postnatal social factors to determine life-long sexual orientation remains to be determined.
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Affiliation(s)
- Jacques Balthazart
- University of Liège, Groupe Interdisciplinaire de Génoprotéomique Appliquée Neurosciences, Research Group in Behavioral Neuroendocrinology, 1 Avenue de l'Hôpital (B36), B-4000 Liège, Belgium.
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