Genetic and environmental influences on individual differences in masculinity, femininity, and gender diagnosticity: analyzing data from a classic twin study.
Analyzing data from Loehlin and Nichols's (1976) classic twin study, we computed measures of Masculine Instrumentality (M), Feminine Expressiveness (F), and Gender Diagnosticity (GD). Quantitative genetic modeling analyses of within-sex individual differences in M, F, and GD indicated that: (1) Additive genetic factors contribute significantly to individual differences in M, F, and GD. (2) The environmental effects on M, F, and GD tend to be nonshared. (3) The genetic and environmental components of individual differences in M, F, and GD tend not to show gender differences. Finally, (4) the estimated within-sex heritability of GD (.53) is significantly greater than the estimated within-sex heritabilities of either M (.36) or F (.38).
Department of Psychology, California State University, Fullerton 92834-6846, USA. rlippa@fullerton.edu
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Hershberger
D000328:Adult; D005260:Female; D005783:Gender Identity; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D010552:Personality Assessment; D012931:Social Environment; D014427:Twins / Q000235:genetics* / Q000523:psychology