Gender equality predicts female over-representation only in competitive domains where they have a relative advantage over males

Nature and nurture perspectives of the gender equality paradox frequently talk past each other because they do not share underlying assumptions regarding which sex differences are inherent. We overcome this limitation by investigating the consequences of a sex difference both perspectives agree is inherent: physical size. We leveraged equestrian sports as a unique test case in which males and females compete together and in which smaller physical size provides a competitive advantage. Findings showed that gender equality is a stronger predictor of female representation in equestrian sports and that countries high in gender equality have the most extreme over-representation of female equestrians, compared to table tennis, judo, swimming, or sailing (total N = 442,453, 128+ countries in each sport). Furthermore, we show that the pattern of findings is inconsistent with the nurture perspective of the gender equality paradox by simulating its assumptions using agent-based modelling and comparing these results to historical data of Olympic equestrians.