Individual Differences in Personality Masculinity-Femininity: Examining the Effects of Genes, Environment, and Prenatal Hormone Transfer

Abstract

Males and females score differently on some personality traits, but the underlying etiology of these differences is not well understood. This study examined genetic, environmental, and prenatal hormonal influences on individual differences in personality masculinity–femininity (M-F). We used Big-Five personality inventory data of 9,520 Swedish twins (aged 27 to 54) to create a bipolar M-F personality scale. Using biometrical twin modeling, we estimated the influence of genetic and environmental factors on individual differences in a M-F personality score. Furthermore, we tested whether prenatal hormone transfer may influence individuals’ M-F scores by comparing the scores of twins with a same-sex versus those with an opposite-sex co-twin. On average, males scored 1.09 standard deviations higher than females on the created M-F scale. Around a third of the variation in M-F personality score was attributable to genetic factors, while family environmental factors had no influence. Males and females from opposite-sex pairs scored significantly more masculine (both approximately 0.1 SD) than those from same-sex pairs. In conclusion, genetic influences explain part of the individual differences in personality M-F, and hormone transfer from the male to the female twin during pregnancy may increase the level of masculinization in females. Additional well-powered studies are needed to clarify this association and determine the underlying mechanisms in both sexes.

Are Sex Differences in Human Brain Structure Associated With Sex Differences in Behavior?

“…Twin studies such as ours estimate a trait’s total heritability. As for behavior, our heritability estimates were in line with those of a previous twin study using a different method with different data (Verweij et al, 2016).…”

Are sex differences in human brain structure associated with sex differences in behaviour?

“…Twin studies like ours estimate a trait's total heritability. As for behaviour, our heritability estimates were in line with those of a previous twin study using a different method with different data (Verweij, Mosing, Ullen, & Madison, 2016).…”

Objectivity and realms of explanation in academic journal articles concerning sex/gender: a comparison of Gender studies and the other social sciences

“…being biologically a man or woman). These and other papers throughout the social sciences find relationships between sex and other variables, such as age, relationship status, parenthood, and many other environmental influences, in patterns predicted by evolutionary theories, in particular those related to differential parental investment, costly signaling, and mate selection (e.g., Buss and Shackelford 2008; Stoet and Geary 2015; Verweij et al 2016; Wåhlin-Jacobsen et al 2015; for reviews, see Buss 2003; Schmitt 2005). It is reasonable to assume that these theoretical perspectives, by and large, explain a substantial proportion of the variance related to group or individual differences, otherwise would these approaches have waned for lack of empirical support.…”