Foetal testosterone, social relationships, and restricted interests in children.

BACKGROUND Sex-differences exist in some areas of human social behaviour. In animals, foetal testosterone (fT) plays a central role in organising the brain and in later social behaviour. fT has also been implicated in language development, eye-contact, and spatial ability in humans. METHODS Fifty-eight children (35 male and 23 female), whose fT was analysed in amniotic fluid, were followed up at age 4. Their mothers completed the Children's Communication Checklist, a questionnaire assessing language, quality of social relationships and restricted interests. RESULTS fT was negatively correlated to quality of social relationships, taking sex-differences into account. fT was also positively correlated with restricted interests in boys. CONCLUSIONS These findings implicate fT in both social development and attentional focus. They may also have implications for understanding the sex ratio in autism.