GENDER-TYPED TOY PLAY IN DIZYGOTIC TWIN PAIRS - A TEST OF HORMONE TRANSFER THEORY

Hormone transfer theory predicts that opposite-sex twins will be affec ted in utero by the hormones their twins produce. This study examines the prediction that opposite-sex dizygotic twins should show less ster eotyped toy play than same-sex dizygotic twins should show less stereo typed toy play than same-sex dizygotic twins as a result of exposure t o opposite-sex hormones in utero. Participants in this study included 32 male-female dizygotic twin pairs, 27 female-female pairs, and 24 ma le-male pairs. All ranged in age from 7 to 12 years and were primarily Caucasian and middle class. Differences in the amount of time childre n played with feminine, masculine, and neutral stereotyped toys during free play were examined. Results did not support hormone transfer the ory. Girls played with feminine toys more than boys and boys played wi th masculine toys more than girls, but there were no significant diffe rences between children with opposite- vs. same-sex twins.