Interpersonal behavior in women: Association with prenatal exposure to sex hormones

Abstract The ratio between the second and fourth digit of the hand (2D:4D ratio) has been used as a marker of prenatal exposure to sex hormones. A previous study found that men with smaller 2D:4D ratios, relative to men with larger ratios, were more agreeable and less quarrelsome with women than with men. We aimed to replicate this study, using a similar procedure for sampling interpersonal behaviors but including participants who were first-year students (n = 81) rather than working adults in a long-term romantic relationship. Event-contingent recording of everyday social interactions yielded data on agreeableness, quarrelsomeness, dominance, and submissiveness in different social contexts (e.g., with male vs. female interaction partners). While we did not replicate the findings previously obtained in men, this might be due to the relatively low number of male participants. Female participants with larger 2D:4D ratios were more agreeable with women than with men; this was not found among women with smaller ratios. Future studies on the link between the 2D:4D ratio and interpersonal behavior should consider with whom interactions take place and examine additional factors such as participants' relationship status and hormonal contraceptive use.