REVISITING THE CRIMINOLOGICAL CONSEQUENCES OF EXPOSURE TO FETAL TESTOSTERONE: A META‐ANALYSIS OF THE 2D:4D DIGIT RATIO*

Abstract

As criminology has become more interdisciplinary in recent years, biosocial criminology has earned a place at the table. Although this perspective comes in many forms, one important proposition has gained increasing attention: that the 2D:4D finger digit ratio—a purported physical biomarker for exposure to fetal testosterone—is related to criminal, aggressive, and risky/impulsive behavior. Strong claims in the literature have been made for this link even though the findings seem to be inconsistent. To establish the empirical status of this relationship, we subjected this body of work to a meta‐analysis. Our multilevel analyses of 660 effect size estimates drawn from 47 studies (14,244 individual cases) indicate a small overall effect size (mean r = .047). Moderator analyses indicate that this effect is rather “general” across methodological specifications—findings that are at odds with theoretical propositions that specify the importance of exposure to fetal testosterone in predicting criminal and analogous behavior later in life. We conclude with a call for exercising caution over embracing the findings from one or two studies and instead highlight the importance of systematically organizing the full body of literature on a topic before making decisions about what does, and what does not, predict criminal and analogous behavior.