Digit Ratios (2D:4D) as Predictors of Risky Decision Making

Many important economic decisions involve financial risk, and there is substantial evidence that women tend to be more risk averse than men. We explore a potential biological basis of the variation in risk-taking within and between men and women using an emerging measure of prenatal androgrens, the ratio between the length of the second and fourth digits (2D:4D). A smaller 2D:4D ratio has been linked to higher exposure to prenatal testosterone relative to estradiol, with men having lower ratios than women on average. In an individual decision-making task with financial stakes, we find that both men and women with smaller 2D:4D ratios chose significantly riskier options. We further find that the 2D:4D ratio can partially explain the overall difference in risktaking between men and women. Moreover, for men and women at the extreme ends of the digitratio distribution the difference in risk-taking disappears entirely. Thus, the 2D:4D ratio can at least partially explain variation in financially motivated risk-taking behavior both within and between sexes and offers strong evidence of a biological basis of attitudes toward risk-taking.