Evidence for a Gene-Environment Interaction in Predicting Behavioral Inhibition in Middle Childhood

TLDR

Gene‑environment interactions are thought to shape early human behavior, yet no human study has shown that they produce stable individual differences in fear responses, despite the serotonin transporter polymorphism being linked to serotonin activity. The study aimed to test whether an interaction between children’s 5‑HTT promoter polymorphism and maternal social support predicts behavioral inhibition toward unfamiliar peers in middle childhood. They assessed children’s 5‑HTT genotype and mothers’ social support ratings to evaluate their interaction on behavioral inhibition toward unfamiliar peers. Children carrying the short 5‑HTT allele and experiencing low maternal social support were at higher risk for behavioral inhibition in middle childhood.

Abstract

Gene-environment interactions are presumed to shape human behavior during early development. However, no human research has demonstrated that such interactions lead to stable individual differences in fear responses. We tested this possibility by focusing on a polymorphism in the promoter region of the gene for the serotonin transporter (5-HTT). This polymorphism has been linked to many indices of serotonin activity. Specifically, we tested the hypothesis that an interaction between children's 5-HTT status and maternal reports of social support predicts inhibited behavior with unfamiliar peers in middle childhood. Results were consistent with this hypothesis: Children with the combination of the short 5-HTT allele and low social support had increased risk for behavioral inhibition in middle childhood.