SENSATION SEEKING IN OPPOSITE-SEX TWINS - AN EFFECT OF PRENATAL HORMONES

Intrauterine hormones and position with respect to male and female lit termates influence sexually dimorphic adult behavior in litter-bearing animals. Opposite-sex dizygotic twins offer the opportunity to examin e analogous effects on sex-related human behaviors. To illustrate this approach, Sensation Seeking Scale (SSS) scores from 422 British twin pairs, including 51 opposite-sex pairs (Zuckerman, M., et al., J. Cons ult. Clin. PsychoL 46:139-149, 1978), were reanalyzed. Zuckerman et al . (1978) have shown that some aspects of sensation seeking are consist ently increased in males relative to females. In comparing age-adjuste d data for opposite and same-sex twins, our reanalysis demonstrated th e predicted increase in sensation seeking in female members of opposit e-sex pairs. Results were significant for measures of disinhibition, e xperience seeking, and overall sensation seeking. In contrast, male op posite-sex twins were not significantly different from male same-sex t wins. Although psychosocial explanations of the increased sensation se eking in opposite-sex female twins cannot be excluded, these findings are consistent with hypothesized in utero hormonal influences on later behavioral development.