1
|
Segal NL, Niculae FJ, Becker EN, Shih EY. Reared-apart/reared-together Chinese twins and virtual twins: Evolving research program and general intelligence findings. J Exp Child Psychol 2021; 207:105106. [PMID: 33743413 DOI: 10.1016/j.jecp.2021.105106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/25/2022]
Abstract
China's One-Child Policy (1979-2015) limited rural families to two children and urban families to one child. This practice, which led to the abandonment of hundreds of thousands of female infants, is indirectly responsible for the separate placement of infant twins. The availability of this sample launched the first prospective study of these pairs. Participants include families and twins comprising 15 monozygotic (MZA) pairs and 7 dizygotic (DZA) pairs from countries throughout the world. The research program is described, and the initial wave of IQ scores for MZA and DZA twin pairs is examined in the first comprehensive report from this study. The twins' mean age at participation was 9.41 years (SD = 6.36), and their ages ranged from 3.19 to 24.98 years. Informative contrasts with adopted-together Chinese twins and virtual twins (same-age unrelated individuals reared together) highlight shared genetic and environmental effects on intellectual development. Applied directions based on findings from these novel samples are described.
Collapse
Affiliation(s)
- Nancy L Segal
- Department of Psychology, California State University, Fullerton, Fullerton, CA 92834, USA.
| | - Francisca J Niculae
- Department of Psychology, California State University, Fullerton, Fullerton, CA 92834, USA
| | - Erika N Becker
- Department of Psychology, California State University, Fullerton, Fullerton, CA 92834, USA
| | - Emmy Y Shih
- Department of Psychology, California State University, Fullerton, Fullerton, CA 92834, USA
| |
Collapse
|
2
|
Twenge JM, Campbell WK. Age and Birth Cohort Differences in Self-Esteem: A Cross-Temporal Meta-Analysis. PERSONALITY AND SOCIAL PSYCHOLOGY REVIEW 2016. [DOI: 10.1207/s15327957pspr0504_3] [Citation(s) in RCA: 296] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
A meta-analytic review finds that college students' self-esteem increased substantially between 1968 and 1994 when measured using the Rosenberg Self-Esteem Scale (RSE). Children's scores on the Coopersmith Self-Esteem Inventory (SEI) show a curvilinear pattern over time, decreasing from 1965 to 1979 and increasing from 1980 to 1993. Children's SEI scores are directly correlated with social statistics (e.g., divorce rate, unemployment) for the corresponding years. Analyses for age differences find that SEI scores decrease slightly during the transition from elementary school to junior high and then rise progressively through high school and college. RSE scores increase steadily with age. Results are discussed in terms of the antecedents of self-esteem, including social acceptance, competencies, and the culture of self-worth.
Collapse
|
3
|
Eaves LJ, Heath AC, Neale MC, Hewitt JK, Martin NG. Sex differences and non-additivity in the effects of genes on personality. ACTA ACUST UNITED AC 2012. [DOI: 10.1375/twin.1.3.131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractNew large-sample data show that non-additive genetic effects, probably epistatic interactions between loci, and sex-limited gene expression are significant features of the genetic architecture of human personality as measured by questionnaire scales of extraversion and neuroticism. Three large data sets – new data on large samples (n = 20 554) of US twins, their spouses, parents, siblings and children, correlations for Australian twins (n = 7 532), and previously published twin data from Finland (n = 14 288) – are subjected to an integrated analysis to test alternative hypotheses about the genetic causes of family resemblance in personality. When allowance is made for differences in reliability of the scales, the combined data are consistent with the same model for variation. There are significant amounts of genetic non-additivity for both dimensions of personality. The evidence favours additive × additive epistatic interactions rather than dominance. In the case of neuroticism, there is especially strong evidence of sex differences in genetic architecture favouring a greater relative contribution of non-additive genetic effects in males. The data confirm previous claims to find no major contribution of the shared environment of twins and siblings to these dimensions of personality. Correlations between spouses are zero, and the correlations for very large samples of siblings and non-identical twins do not differ significantly.
Collapse
|
4
|
Eaves L, Heath A, Martin N, Maes H, Neale M, Kendler K, Kirk K, Corey L. Comparing the biological and cultural inheritance of personality and social attitudes in the Virginia 30 000 study of twins and their relatives. ACTA ACUST UNITED AC 2012. [DOI: 10.1375/twin.2.2.62] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractMeasures of four dimensions of personality (Psychoticism, Extraversion, Neuroticism, and Lie scores) and six aspects of social attitudes (to sex, taxation, militarism, politics, religion and a general conservatism scale) were obtained by mailed questionnaire from 29 691 US subjects including adult twins (n = 14 761) their parents (n = 2360), their spouses (n = 4391), siblings (n = 3184) and adult children (n = 4800). After correction for the average effects of age, sex and source of sample, familial correlations were computed for 80 distinct biological and social relationships. The data allow for the estimation of the additive and non-additive effects of genes, assortative mating, vertical cultural inheritance and other non-parental effects of the shared environment on differences in personality and social attitudes. The interaction of genetic and environmental effects with sex may also be analyzed. Model-fitting analyses show that personality and social attitude measures differ markedly in major features of family resemblance. Additive and dominant genetic effects contribute to differences in both personality and attitudes, but the effects of the family environment, including vertical cultural transmission from parent to child, are much more marked for social attitudes than for personality. There is substantial assortative mating for social attitudes and almost none for personality. The causes of family resemblance depend significantly on sex for almost every variable studied. These findings clarify and extend the more tentative findings derived from previous twin, family and adoption studies.
Collapse
|
5
|
SEGAL NANCYL. The Importance of Twin Studies for Individual Differences Research. JOURNAL OF COUNSELING AND DEVELOPMENT 2011. [DOI: 10.1002/j.1556-6676.1990.tb01425.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
6
|
Twenge JM, Gentile B, DeWall CN, Ma D, Lacefield K, Schurtz DR. Birth cohort increases in psychopathology among young Americans, 1938–2007: A cross-temporal meta-analysis of the MMPI. Clin Psychol Rev 2010; 30:145-54. [DOI: 10.1016/j.cpr.2009.10.005] [Citation(s) in RCA: 308] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 10/15/2009] [Accepted: 10/19/2009] [Indexed: 11/26/2022]
|
7
|
|
8
|
|
9
|
Twenge JM. Changes in women's assertiveness in response to status and roles: A cross-temporal meta-analysis, 1931–1993. J Pers Soc Psychol 2001. [DOI: 10.1037/0022-3514.81.1.133] [Citation(s) in RCA: 220] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
10
|
Joseph J. Potential confounds in psychiatric genetic research: the case of pellagra. NEW IDEAS IN PSYCHOLOGY 2000. [DOI: 10.1016/s0732-118x(99)00038-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
11
|
Heritabilities of Common and Measure-Specific Components of the Big Five Personality Factors. JOURNAL OF RESEARCH IN PERSONALITY 1998. [DOI: 10.1006/jrpe.1998.2225] [Citation(s) in RCA: 193] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
12
|
Borg JG. Are differences between twins a result of mutual rivalry? ACTA GENETICAE MEDICAE ET GEMELLOLOGIAE 1997; 46:23-36. [PMID: 9298156 DOI: 10.1017/s0001566000000726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The sexual index included in the Szondi test makes it possible to define the domains of an individual's "internal sex" or gender-especially the degree of the subject's bisexuality. This index was employed in a comparison between partners reared together in 62 monozygotic and 23 dizygotic pairs of twins. The observed incongruence in 1/3 MZ pairs would not appear to derive totally from errors of measurement. In most of these pairs it is competition which underlies the incongruence seen on the sexual index. It was further observed that the congruence here as in general in female pairs is clearly more marked than in males. A hypothesis was proposed, whereby competition for dominance is a distinctively major-tonality (masculinity) characteristic. The incongruence is more conspicuous among males because males are in general more markedly major-toned than females. This hypothesis was borne out. It is thus necessary here as in general to adopt two sex variables in parallel: external (i.e. matricular) sex and internal sex (gender). It is due to the presence of these competitive pairs that the means and especially deviations of twins' test results will consistently diverge from those in the population at large.
Collapse
Affiliation(s)
- J G Borg
- Department of Psychology, University of Tampere, Finland
| |
Collapse
|
13
|
Sherman SL, DeFries JC, Gottesman II, Loehlin JC, Meyer JM, Pelias MZ, Rice J, Waldman I. Behavioral genetics '97: ASHG statement. Recent developments in human behavioral genetics: past accomplishments and future directions. Am J Hum Genet 1997; 60:1265-75. [PMID: 9199545 PMCID: PMC1716152 DOI: 10.1086/515473] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The field of behavioral genetics has enormous potential to uncover both genetic and environmental influences on normal and deviant behavior. Behavioral-genetic methods are based on a solid foundation of theories and methods that successfully have delineated components of complex traits in plants and animals. New resources are now available to dissect the genetic component of these complex traits. As specific genes are identified, we can begin to explore how these interact with environmental factors in development. How we interpret such findings, how we ask new questions, how we celebrate the knowledge, and how we use or misuse this knowledge are all important considerations. These issues are pervasive in all areas of human research, and they are especially salient in human behavioral genetics.
Collapse
Affiliation(s)
- S L Sherman
- Department of Genetics, Emory University, Atlanta, GA, USA.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Tambs K, Sundet JM, Eaves L, Solaas MH, Berg K. Pedigree analysis of Eysenck Personality Questionnaire (EPQ) scores in monozygotic (MZ) twin families. Behav Genet 1991; 21:369-82. [PMID: 1953599 DOI: 10.1007/bf01065973] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
MZ twins with spouses and children, altogether 811 subjects, completed the Eysenck Personality Questionnaire (EPQ). For extraversion (E), neuroticism (N), and lying (L), models including only additive genetic effects fitted well to the observed sex-specific correlations for the various sets of relationships. There was no evidence of sex differences for any parameter estimate for E, N, and L. The fit for E improved significantly after including dominance, and the fit for L improved significantly after including assortative mating. A model specifying genetic additive and dominance effects and assortative mating fitted well to the Psychoticism (P) data, but the fit improved significantly when a parameter for cultural transmission from fathers to daughters were included. Except for this, there was no evidence of cultural transmission for any scores. The heritabilities for the best-fitting models were .53 (E), .36 (N), .43 (L), and .39 (P). The latter includes almost only nonadditive, and no additive, variance, suggesting an overestimation of this effect due to random fluctuation or environmental sibling effect misinterpreted as dominance.
Collapse
Affiliation(s)
- K Tambs
- Department of Behavioural Sciences in Medicine, University of Oslo, Norway
| | | | | | | | | |
Collapse
|
15
|
Bouchard TJ, Lykken DT, McGue M, Segal NL, Tellegen A. Sources of human psychological differences: the Minnesota Study of Twins Reared Apart. Science 1990; 250:223-8. [PMID: 2218526 DOI: 10.1126/science.2218526] [Citation(s) in RCA: 875] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of intensive psychological and physiological assessment. Like the prior, smaller studies of monozygotic twins reared apart, about 70% of the variance in IQ was found to be associated with genetic variation. On multiple measures of personality and temperament, occupational and leisure-time interests, and social attitudes, monozygotic twins reared apart are about as similar as are monozygotic twins reared together. These findings extend and support those from numerous other twin, family, and adoption studies. It is a plausible hypothesis that genetic differences affect psychological differences largely indirectly, by influencing the effective environment of the developing child. This evidence for the strong heritability of most psychological traits, sensibly construed, does not detract from the value or importance of parenting, education, and other propaedeutic interventions.
Collapse
Affiliation(s)
- T J Bouchard
- Department of Psychology, University of Minnesota, Minneapolis 55455
| | | | | | | | | |
Collapse
|
16
|
Abstract
Traditional behavioral genetic methods involve the use primarily of family, twin, and adoption correlations to estimate the relative contributions of genetic and environmental influences in the etiology of individual differences. These methods and representative results for personality are described. However, newer methods are emphasized: structural models and model-fitting, multivariate analysis, genetic change and continuity in development, shared and non-shared components of environmental variance, and genetic components of "environmental" variation. Because most applications of these behavioral genetic methods to the study of personality involve self-report omnibus questionnaires, an important direction for future research in this area is to use these methods to explore new issues and new measures that have emerged from personality theory and research during the past decade.
Collapse
|