Individual differences in trust evaluations are shaped mostly by environments, not genes

Rapid impressions of trustworthiness can have extreme consequences, impacting financial lending, partner selection, and death-penalty sentencing decisions. But to what extent do people disagree about who looks trustworthy, and why? Here, we demonstrate that individual differences in trustworthiness and other impressions are substantial and stable, agreeing with the classic idea that social perception can be influenced in part by the “eye of the beholder.” Moreover, by examining twins, we show that individual differences in impressions of trustworthiness are shaped mostly by personal experiences, instead of genes or familial experiences. Our study highlights individual social learning as a key mechanism by which we individually come to trust others, with potentially profound consequences for everyday trust decisions.