The preindustrial family structure instilled family members with values that passed through generations and impact today's political attitudes and policies. Three studies show that ancestral kinship structure predicts right-wing cultural attitudes and, among those less engaged in politics, left-wing economic attitudes (though controlling for the country of residence removes this prediction). Stronger country-level ancestral kinship strength also increases anti-LGBT policies and welfare spending. This work indicates that political beliefs are rooted in the value systems and familial institutions created by our forebears.