Abstract Focusing on the 1994 genocide in Rwanda, we examine how sibling relationships—one of the most salient familial bonds—influence individual engagement in violence during mass atrocity. Drawing on an adaptation of differential association and social learning theories for contexts of mass atrocity, we analyze a novel dataset linking over 300,000 siblings from Rwanda's post‐genocide gacaca court records. We find that the probability an individual perpetrated interpersonal violence (rather than property crime) increased significantly with the proportion of their siblings who did so. Complementing this quantitative analysis with 38 in‐depth interviews with individuals convicted of genocidal violence, we identify several specific mechanisms that help explain this aggregate relationship, such as imitation, restraint, and coercion. Our findings extend classical criminological theories on sibling delinquency to extraordinary contexts of societal breakdown, carrying broader implications for research at the intersection of violent crime, collective behavior, and social networks.
Wippell et al. (Mon,) studied this question.