5‑HTTLPR polymorphism and cross‑cultural adaptation: the role of relational openness as a mediator

Prior evidence suggests increased social interaction anxiety among carriers of the short (s) allele of the serotonin transporter gene polymorphism (5-HTTLPR), relative to the long (l) allele carriers. According to gene-culture coevolution hypothesis, the collectivistic norm of lower levels of relational openness (i.e., lesser inclinations to meet new people) and 5-HTTLPR s allele co-evolved under the environmental pressure of high pathogen prevalence. We examined if the 5-HTTLPR s allele and low relational openness are associated at the levels of the society and the individual. In Study 1, we found across 21 countries, those with a higher prevalence of the l allele of 5-HTTLPR (L%) tend to be higher in relational mobility. In Study 2, 303 international students were genotyped, and questionnaires examined their personal tendencies during their cross-cultural adaptation process. The s allele carriers (s/s homozygotes & s/l heterozygotes) were found to have higher relational openness than the non-carriers (l/l homozygotes). Moreover, 5-HTTLPR was found to have an indirect effect on cross-cultural adaptation and cultural diversity in friendship networks, mediated by relational openness. Those lower in relational openness encountered more challenge in adapting to the new country and developed friendship networks that were culturally less diverse. Together, the findings imply the gravity of relational openness as a confluence of gene-culture coevolution, with key importance for social networks and the newcomers’ cross-cultural adaptation in the multicultural environment.