The Mingling of Nations : Racial Divide, Partner Mistrust, and STIs

In societies organized around distinct racial and ethnic groups, limited communication between these groups might increase the search cost of sexual partners outside of own group, leading to racially segregated sexual networks and low risks of sexually transmitted infections (STIs). At the same time, because sexual infidelity is more likely to be discovered when the cheated-upon individuals are co-ethnics, individuals in multiracial societies might find it cheaper to select sexual partners from diverse ethnic groups to hide their infidelity, which would lead to large interethnic sexual networks and high risks of STIs. We propose a model to capture these conflicting hypotheses. We test it by analyzing the causal effect of neighborhood-level racial diversity on sexual activity and STIs, using unique individual-level data from England, Wales, and Scotland. We find that individuals residing in multiracial neighborhoods have a greater number of sexual partners and are more likely to be infected with a wide range of STIs than their counterparts residing in more racially homogeneous neighborhoods. We use traditional and new instrumental variables approaches, placebo tests, and various robustness checks to establish causation. We document three related mechanisms. First, mistrust in partner loyalty is higher in more racially diverse neighborhoods, with this positive relationship being only present among individuals involved in inter-racial relationships. Second, we find that in racially diverse neighborhoods, individuals involved in inter-racial relationships are more likely to be infected with STIs, holding constant the number of sexual partners and other individual characteristics. Third, individuals residing in more racially diverse neighborhoods are more likely to be involved in concurrent and overlapping sexual relationships, inducing large sexual networks. From a policy perspective, our analysis implies that policies that promote racial and ethnic integration are likely to reduce unhealthy sexual activity and the spread of STIs in racially and ethnically diverse societies