Do genes contribute to the "gender gap"?

The nature and mechanisms underlying the differences in political preferences between men and women continues to be debated with little consideration for the biology of sex. Genetic influences on social and political attitudes have been reported for each sex independently, yet neither the magnitude nor sources of genetic influences have been explored for significant differences between males and females. In a large sample of adult twins, respondents indicated their attitudes on contemporary social and political items. Finding significant differences in the magnitude of genetic, social, and environmental variance for political preferences, and the potential for different genes in males and females to influence these phenotypes, we provide evidence that sex modulates the effects of genetic and environmental differences on political preferences.