This is an important study from the Psychological Science journal’s early view:
Fetal Testosterone Predicts Sexually Differentiated Childhood
Behavior in Girls and in Boys
Bonnie Auyeung, Simon Baron-Cohen, Emma Ashwin, Rebecca Knickmeyer, Kevin Taylor, Gerald Hackett, and Melissa Hines
ABSTRACT—Mammals, including humans, show sex differences in juvenile play behavior. In rodents and nonhuman primates, these behavioral sex differences result, in part, from sex differences in androgens during early development. Girls exposed to high levels of androgen prenatally, because of the genetic disorder congenital adrenal hyperplasia, show increased male-typical play, suggesting similar hormonal influences on human development, at least in females. Here, we report that fetal testosterone measured from amniotic fluid relates positively to male-typical scores on a standardized questionnaire measure of sextypical play in both boys and girls. These results show, for the first time, a link between fetal testosterone and the development of sex-typical play in children from the general population, and are the first data linking high levels of prenatal testosterone to increased male-typical play behavior in boys.
Here’s the money quote:
Thus, our data are the first documentation that androgen exposure prenatally relates to sexually differentiated play behavior in boys and in girls. In addition, the current results support an organizational, as opposed to current, activational role of testosterone, because play behavior is measured in childhood, when concurrent testosterone levels are low.
Gender non-conformity is the strongest predictor of same-sex attraction in adulthood. This study links prenatal testosterone with later gender typical behavior. The brains of children are organized in ways that react to their environment in socially typical or atypical ways. How such behavior shapes the family environment is unclear, however, it does not appear that the behavior is exclusively a response to parental bonding or modeling.