The study tests gene-environment interactions for explaining cross-national differences in social hierarchy values and beliefs. Greater threats are predicted to be associated with stronger endorsement and support of social hierarchies in the presence of population genetic deficiencies in processing threat-related information. Predictions are tested with data from 28 societies, focusing on hierarchical dominance values in teachers and student samples (28 societies) and support for central authority in representative samples (21 societies). The interaction between greater population frequency of short alleles of the 5-HTT serotonin transporter gene and presence of threats was significant in six out of the eight regressions. I discuss the findings in the larger context of interdependencies between biological and cultural processes and the importance of broadening our tool kit for studying cultural differences.