Serotonin receptor 2A gene moderates the effect of childhood maternal nurturance on adulthood social attachment.

The ability to form and maintain attachment relations with other people is crucial for mental health and well-being. The origins of attachment behaviors are often assumed to be in early experiences with other people, especially with primary caregivers. Preliminary evidence suggests that serotonergic system may be involved in attachment behaviors. We examined whether the T102C variant of the serotonin receptor 2A gene moderates the effect of childhood maternal nurturance on social attachment in adulthood. The participants were 1070 women and men from the Young Finns Study with 27-year follow-up and two measurement times for the outcomes (n = 1836 person observations). Mothers reported their relationship quality with their children (participants) in childhood or adolescence. Social attachment was assessed by participant's self-reports on two measures (reward dependence scale of the Temperament and Character Inventory and the Relationship Questionnaire). High childhood maternal nurturance predicted high reward dependence and low avoidant attachment in carriers of the T/T genotype but not in the T/C or C/C genotype groups, while low maternal nurturance was associated with low reward dependence and high avoidant attachment in T/T genotype carriers but not in C allele carriers. Our result suggests that T/T genotype carriers were more influenced by their childhood nurturing environment, than their C allele carrying counterparts, thus providing evidence for differential susceptibility to childhood nurturing environment associated with the HTR2A gene.