This article explores whether the practice of cousin marriage helps explain the persistence of honor cultures and honor killings. The authors have hypothesized that cousin marriage can create kin benefits but also parent–offspring conflict, leading to the evolution of honor norms and punitive practices to enforce cousin marriages. Using genomic inbreeding coefficients as a proxy for historical cousin marriage across 52 ethnic groups, these practices are likely to enforce these marriages across regions within countries. The conclusion is that honor cultures may be rooted in kinship dynamics, particularly conflicts surrounding consanguineous marriage. Authors do raise evolutionary puzzle of why female victims are harmed by blood kin.