Evidence documenting associations between 5-HTTLPR and parenting behavior led to testing the hypothesis that this polymorphism moderates the effect of the quality of environmental context on maternal sensitivity. Participants were 210 Portuguese mothers and their preschool children, recruited from the community. An index reflecting the quality of the environmental context was derived based on nine markers (e.g. single parenthood; parental education, economic difficulties, family conflict, maternal psychopathology). Maternal sensitivity was measured observationally. Maternal saliva was collected with OraGene kits for genetic analysis. Results revealed a gene-X-environment interaction, such that short-allele homozygotes proved more sensitive to the family context than long-allele carriers (i.e. sL/LL), displaying the highest and lowest levels of maternal sensitivity, depending on, respectively, low and high quality levels of the environmental context. Because even mothers carrying the long allele evinced similar responsiveness to the environmental context, but to a lesser extent, findings proved consistent with the weak differential susceptibility model of person-X-context interaction. Results are discussed in light of prior and related gene-X-environment findings.

The oxytocinergic system is a primary biological system involved in regulating a child's needs for bonding and for protection from threats. It is responsive to social experiences in close relationships, though evidence across studies is not entirely consistent. Guided by previous literature, we investigated individual and environmental factors predicting and presumably affecting children's oxytocin (OT) response during mother-child interaction. by focusing on children's OXTR genotype, and maternal behavior, respectively. This was achieved by assessing salivary OT levels of 88 Portuguese preschoolers prior to and following a mother-child interaction task, and by genotyping children's OXTR SNP rs53576. Maternal interactive behavior was assessed using Ainsworth scales. Results indicated that child genotype and mother's sensitive responsiveness interacted in predicting change in child OT concentrations from before to after the interaction. Specifically, Genotypic differences emerged under conditions of low maternal sensitive responsiveness: OT levels increased over time for children with the GG genotype when maternal sensitive responsiveness was low, but no such genotypic differences were evident when mothers were highly sensitive responsive. Findings provide preliminary support for the notion that increased understanding of children's OT and close relationships requires consideration of both individual and environmental factors.