Common Genetic Effects of Gender Atypical Behavior in Childhood and Sexual Orientation in Adulthood: A Study of Finnish Twins
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The existence of genetic effects on gender atypical behavior in childhood and sexual orientation in adulthood and the overlap between these effects were studied in a population-based sample of 3,261 Finnish twins aged 33–43 years. The participants completed items on recalled childhood behavior and on same-sex sexual interest and behavior, which were combined into a childhood gender atypical behavior and a sexual orientation variable, respectively. The phenotypic association between the two variables was stronger for men than for women. Quantitative genetic analyses showed that variation in both childhood gender atypical behavior and adult sexual orientation was partly due to genetics, with the rest being explained by nonshared environmental effects. Bivariate analyses suggested that substantial common genetic and modest common nonshared environmental correlations underlie the co-occurrence of the two variables. The results were discussed in light of previous research and possible implications for theories of gender role development and sexual orientation.
KeywordsGender identity Gender role behavior Sexual orientation Sex differences Behavior genetics
This research was financed by Grant No. 210298 from the Academy of Finland and a Centre of Excellence Grant from the Stiftelsen för Åbo Akademi Foundation and personal grants to the first author from the Signe and Ane Gyllenberg Foundation, the Waldemar von Frenkell Foundation, and the Stiftelsen för Åbo Akademi Foundation.
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