AbstractFamilies are not only the first institution ever created, they are also, for most people, the first institution ever encountered. The preindustrial family structure, which was a function of local ecology and cooperation needs, instilled family members with different values, such as trust in strangers and respect for elders. These values passed through generations and, as we show in three studies, impact today's political attitudes and policies. First, using surveys of second-generation immigrants representing roughly 180 ethnicities living in 32 European countries, we show that the tighter kinship structure of a person's ancestors predicts right-wing cultural attitudes. Among those who are less engaged in politics, tighter ancestral kinship structure also predicts left-wing economic attitudes. In a second study, we control for country-level differences by comparing ethnic groups within countries and find that ancestral kinship strength predicts right-wing cultural attitudes but not left-wing economic attitudes. Finally, in a third study, we examine the policy implications of ancestral kinship. We show that stronger country-level ancestral kinship strength also increases anti-LGBT policies and welfare spending. Finally, we examine whether value systems link preindustrial kinship with modern political attitudes. In total, this work indicates that our political beliefs are rooted in the value systems and familial institutions created by our forebears.