Serotonin Transporter Gene Polymorphisms and Maternal Overprotection Regulate Adult Social Expectations on Close Relationships

Abstract

Humans are evolutionary-driven to adult mating and conceive social expectations on the quality of their affiliations. The genetic susceptibility to adverse environments in critical periods can alter close relationships. The current research investigates how the promoter region of the Serotonin Transporter Gene (5-HTTLPR) and perceived caregiving behavior in childhood could influence the social expectations on close adult relationships. For this purpose, 5-HTTLPR data was collected from the buccal mucosa of 65 Italian individuals (33 males). The participants filled (a) the Parental Bonding Instrument (PBI) to provide the levels of care and overprotection from mother and father, and (b) the Experience in Close Relationships-Revised (ECR-R) to report the social expectations on the intimate relationship assessed in terms of anxiety and avoidance from the partner. An interaction effect between 5-HTTLPR and PBI dimensions on the ECR-R scores was hypothesized. Results confirmed that the interplay between the genetic groups and history of maternal overprotection predicted avoidance experienced in romantic relationships in adulthood. Moreover, both adult anxiety and avoidance felt in an intimate relationship were found to covary as a function of maternal overprotection. The present work proposes further evidence of the genetic and parental mechanisms regulating social expectations involved in close relationships.

Keywords: 5HTTLPR; anxiety; attachment; avoidance; close relationship; gene*environment; maternal overprotection; parent-infant interaction; parental bonding; serotonin transporter gene.

Figure 1

(A) Main effect of recalled maternal overprotection in childhood on adult anxiety in close relationships. Pearson r coefficients between the early maternal overprotection and anxiety. The line represents the linear model for the total sample. (B) Anxiety mean scores by low and high maternal overprotection. (C) The main effect of recalled maternal overprotection in childhood on adult avoidance in close relationships. Pearson r coefficients between the early maternal overprotection and avoidance. The line represents the linear model for the total sample. (D) Avoidance mean scores by low and high maternal overprotection.

Figure 2

(A) Interaction between 5-HTTLPR and maternal overprotection on avoidance. Pearson r coefficients between the avoidance scores and the recalled maternal overprotection for each genetic group. Blue circles = L-carriers; pink triangles = S/S. Continuous lines represent the linear models for L-carriers (blue) and S/S homozygous (pink). Dashed lines represent the standard error of the regression lines for L-carriers (blue) and S/S homozygous (pink). (B) Avoidance mean scores in L-carriers (blue) and S/S homozygous (pink) by low and high maternal overprotection.