Carving the Biodevelopment of Same-Sex Sexual Orientation at Its Joints

Sexual and Gender Diversity in Thailand: Associations with Recalled Childhood Sex-Typed Behavior and Adulthood Occupational Preferences

Same-sex attracted individuals report greater levels of sex-atypical childhood behaviors and adulthood occupational preferences when compared with their heterosexual counterparts. While these sexual orientation differences are well established, the extent to which gender-role presentation relates to such differences is unclear. The present study examined recalled childhood sex-(a)typical behaviors (CSAB) and adulthood occupational preferences in a diverse Thai sample (N = 1294) of cisgender heterosexual men (n = 270) and women (n = 280), gay men (n = 199), lesbian women (n = 56), and unique Thai sexual orientation/gender categories: sao praphet song (i.e., feminine-presenting same-sex attracted males; n = 166), toms (i.e., masculine-presenting same-sex attracted females; n = 174), and dees (i.e., feminine-presenting females sexually attracted to toms; n = 149). Gay men and sao praphet song reported more CSAB and sex-atypical adulthood occupational preferences than heterosexual men, and sao praphet song were more sex-atypical than gay men. Toms reported more CSAB and sex-atypical adulthood occupational preferences than heterosexual women, lesbian women, and dees, whereas lesbian women were more sex-atypical than heterosexual women and dees in childhood but not adulthood. CSAB was associated with sex-atypical adulthood occupational preferences among heterosexual men and all same-sex attracted groups, indicating continuity in gender-role expression development. Overall, this study replicates previous findings indicating greater sex-atypical behaviors and interests during childhood and adulthood among same-sex attracted individuals. It also expands upon prior literature by showing how gender-role presentation relates to these sexual orientation differences among males and females.

Worldwide study reveals fluid sexual preferences in females and no association between gynephilia and non-heterosexuality

BACKGROUND

Social factors and a lack of clearself-awareness may prevent women from explicitly reporting their non-heterosexuality, and implicit measures could provide more reliable data.

AIM

This study examined non-heterosexuality and gynephilia in a large, global sample of women using implicit and explicit methods.

METHODS

A sample of 491 women participated in this cross-sectional study. Participants completed a biographical questionnaire, the Autobiographical-Implicit Association Test, the Sexual Preference-Implicit Association Test (SP-IAT), and an explicit measure of sexual orientation. In a follow-up study, 263 participants were recontacted and completed the Autobiographical Sexual Orientation IAT and answered additional questions about their sexual behavior and preferences related to the stimuli on the SP-IAT.

OUTCOMES

The main outcome measures were D-scores on implicit association tests and scores on explicit measures of sexual orientation and behaviors.

RESULTS

Implicit measures showed a higher rate of gynephilia (67.8%) than explicit non-heterosexuality (19.6%), with consistent results across continents. The findings suggest that women may be attracted to other women without necessarily desiring sexual encounters with them. Furthermore, the results suggest a degree of fluidity in sexual preferences in the female population.

CLINICAL IMPLICATIONS

Studying the prevalence of gynephilia and non-heterosexuality in adult women can inform the development of health promotion programs tailored to women's diverse sexual experiences and preferences.

STRENGTHS & LIMITATIONS

Strengths include the global sample and the use of both implicit and explicit measures. Limitations involve the cross-sectional web-based design, potential sample biases, and aspects related to the validity of the SP-IAT.

CONCLUSION

Implicit measures of non-heterosexuality appear to be less tied to social factors than explicit assessments. In women, gynephilia may not necessarily serve as a proxy for non-heterosexuality. Moreover, women seem to exhibit greater fluidity in sexual preferences and behaviors than men.

Biodevelopmental Correlates of Sexual Orientation in Men: Evidence from a Polish Sample

Biological mechanisms proposed to play a role in the development of sexual orientation in men include hormonal, genetic, and immunological factors. The posited roles of these factors are not mutually exclusive; instead, they may be at play to different degrees in different individuals. Direct measurement of these influences is challenging; thus, researchers rely on putative markers. We collected data on five well-established markers in a sample of gay and heterosexual men. We then (1) compared the levels of those markers in gay and straight men, (2) identified latent profiles based on those markers, and (3) compared the proportions of gay and straight men within the profiles. Gay men reported less gender conformity in childhood, a higher proportion of older brothers, were more right-handed, had more non-heterosexual relatives, and had more feminized digit ratios. Of the six identified profiles, the most numerous, containing a significantly higher proportion of straight men, had masculine digit ratios, masculine behavior in childhood, and was the most right-handed. Proportions of gay and straight men did not differ in the profile with the most feminine digit ratio, the profile associated with the highest proportion of older brothers, and the profile associated with left-handedness. Two remaining profiles, associated with familiality, and the most feminine childhood gender behaviors, consisted predominantly of gay men. The study suggests that further investigations of differences within sexual orientation categories are warranted.

The standardization of a new Explicit Pornographic Picture Set (EPPS)

Pictures with affective content have been extensively used in scientific studies of emotion and sexuality. However, only a few standardized picture sets have been developed that offer explicit images, with most lacking pornographic pictures depicting diverse sexual practices. This study aimed to fill this gap through developing a standardized affective set of diverse pornographic pictures (masturbation, oral sex, vaginal sex, anal sex, group sex, paraphilia) of same-sex and opposite-sex content, offering dimensional affective ratings of valence, arousal, and dominance, as well as co-elicited discrete emotions (disgust, moral and ethical acceptance). In total, 192 pornographic pictures acquired from online pornography platforms and 24 control IAPS images have been rated by 319 participants (Mage = 22.66, SDage = 4.66) with self-reported same- and opposite-sex sexual attraction. Stimuli were representative of the entire affective space, including positively and negatively perceived pictures. Participants showed differential affective perception of pornographic pictures according to gender and sexual attraction. Differences in affective ratings related to participants' gender and sexual attraction, as well as stimuli content (depicted sexual practices and sexes). From the stimuli set, researchers can select explicit pornographic pictures based on the obtained affective ratings and technical parameters (i.e., pixel size, luminosity, color space, contrast, chromatic complexity, spatial frequency, entropy). The stimuli set may be considered a valid tool of diverse explicit pornographic pictures covering the affective space, in particular, for women and men with same- and opposite-sex sexual attraction. This new explicit pornographic picture set (EPPS) is available to the scientific community for non-commercial use.

Fertility of Czech Gay and Straight Men, Women, and Their Relatives: Testing the Sexually Antagonistic Gene Hypothesis

One proposal for the persistence of homosexuality in the human population is the sexually antagonistic gene hypothesis, which suggests that the lower fertility of homosexual individuals, especially men, may be compensated by higher fertility of their relatives of the opposite sex. To test this hypothesis, we have collected data from 7,312 heterosexual men, 459 gay men, 3,352 heterosexual women, and 79 lesbian women mainly from Czechia. In an online survey, participants answered questions regarding their own as well as their parents' and grandparents' fertility. For men, we obtained no significant results except for higher fertility of gay men's paternal grandmothers, but the magnitude of this effect was very small. For the female sample, we recorded lower fertility of lesbian women's mothers and fathers. In line with our expectations, both gay men and lesbian women had lower fertility rates than their heterosexual counterparts. Our results are consistent with recent studies which likewise do not support the sexually antagonistic gene hypothesis.

Recalled Childhood Separation Anxiety in Relation to Sex, Sexual Orientation, and Gender Identity in Thailand

Same-sex sexual attraction is an evolutionary paradox. It is influenced by genes but also associated with reduced reproduction. An altruistic disposition toward kin could increase relatives' reproduction, thus addressing this paradox. Developmentally, such a disposition may manifest as anxiety during separation from kin. This hypothesis has been supported among androphilic (i.e. sexually attracted to males) males, but few similar studies of gynephilic (i.e. sexually attracted to females) females exist. We examined recalled childhood separation anxiety in Thailand and employed the largest and most sexually and gender-diverse sample to date (N = 1403). Among heterosexuals, men recalled less concern for parents' and siblings' well-being during separation than women. Androphilic males evidenced elevated concern for parents' and siblings' well-being during separation, and transfeminine androphilic males known as sao praphet song reported heightened anxiety when separated from parents. Among females, transmasculine gynephilic females known as toms recalled less concern about parents' well-being during separation than feminine females who are attracted to toms and known as dees. Bisexual women recalled less anxiety when separated from parents than dees and lesbian and heterosexual women. These findings suggest a disposition toward heightened kin-directed altruism is evident in childhood among androphilic males, but not gynephilic females.

Parental Income and the Sexual Behavior of Their Adult Children: A Trivers-Willard Perspective

Parental income is negatively and linearly related to the digit ratio (2D:4D; a proxy for prenatal sex steroids) of their children. Children of parents with high income are thought to be exposed to higher prenatal testosterone and develop lower 2D:4D. It is further hypothesized that 2D:4D relates to sexual orientation, although it is unclear whether the association is linear or curvilinear. Here, we consider patterns of parental income and its association with the sexual behavior of their adult children in a large online study (the BBC internet study). There were curvilinear relationships with parental income in male and female children. The highest frequencies of homosexuality and bisexuality were found in the lowest income group (bottom 25% of the population), the lowest frequencies in the income group representing the upper 50% of the population, and intermediate values in the other groups (low 50% and top 25% of the population). Parental income showed a U-shaped association with scores for same-sex attraction and an inverted U-shaped association with opposite-sex attraction. Thus, for the first time, we show that same-sex attraction is related to parental income. The curvilinear relationship between parental income and sexual behavior in their adult children may result from an association between very high fetal estrogen or testosterone and attraction to partners of the same sex. Among non-heterosexuals, and in both sexes, very high fetal estrogen may be associated with femme or submissive sexual roles, and very high fetal testosterone with butch and assertive sexual roles.