The Association Between the Postnatal Environment and Behavioral Sexual Dimorphism in Pre-school Children in Single-Child Families in Qingdao, China

Abstract

Previous studies have shown that prenatal exposure to chemical or non-chemical endocrine disruptors can alter children’s sexually dimorphic behavior. To date, no study has examined the possible influence of postnatal-environmental factors on the gender-specific play behavior of childhood. We hypothesized that the postnatal environment in early childhood might also influence the sexual dimorphism of the brain. Parents or guardians of pre-school children completed questionnaires about their postnatal living environment. The Pre-School Activities Inventory (PSAI) was used to measure sexually dimorphic play behavior. Sex-stratified analyses revealed that the generosity (β = 0.085, p < 0.05) and education (β = 0.142, p < 0.01) of fathers predicted higher feminine scores in girls and lower feminine (β = -0.144, p < 0.001) or higher masculine scores (β = 0.129, p < 0.01) in boys. Indices of chemical exposure (i.e., indoor decoration, biomass pollution, hand cleanliness, and passive smoking) had an association with PSAI scores in both girls and boys. Patterns of sensory processing, including tactile and proprioceptive senses scores and sensory underresponsivity scores, also were associated with PSAI scores. An association of PSAI scores with taking drugs during pregnancy and gestational nutrition was evident only in boys. Our results indicate that a social environment of parental guidance and an indoor environment of exposure to chemical are associated with behavioral sexual dimorphism. Children’s patterns of sensory processing also contributed to behavioral sexual dimorphism. Information about the gestational environment also should be considered when studying the development of sexual dimorphism in boys.