BACKGROUND Social cognitive skills are those which enable understanding of social situations; they are relevant to a variety of psychiatric disorders including autism, schizophrenia and externalizing behaviour problems in children.

AIMS To examine the heritability of social cognitive skills.

METHOD Using a population-based sample of twins aged 5-17, the genetic and environmental influences on social cognitive skills were examined.

RESULTS Male scores were higher than female scores (P < 0.001), indicating poorer social cognition among males. A heritability of 0.68 (95% CI 0.43-0.78) was found, with shared environmental influences accounting for only 0.05 of the variance (95% CI 0.00-0.28). This could be removed from the model without worsening the fit. There were no significant differences in genetic effects between the genders, but age-related changes were found, with younger twins showing greater genetic influence on social cognition.

CONCLUSIONS Social cognition appears to be under considerable genetic influence in the population and shows significant male-female differences. No gender differences in genetic influences on the variance of scores were found, but the effects of age were significant.