Abnormal sexual development and psychosexual issues.

Animal models of gonadal hormone influences on the sexual differentiation of brain and behaviour are reviewed and discussed as a basis for predicting hormonal influences on human neurobehavioural development. Behavioural outcomes in clinical intersex cases, including congenital adrenal hyperplasia, androgen insensitivity syndrome, enzymatic deficiencies and situations in which hormones have been prescribed during pregnancy are reviewed. It is concluded that the prenatal or neonatal hormone environment contributes to the development of human behaviours that show sex differences, particularly childhood play behaviour, sexual orientation and core gender identity. There also is some evidence for influences on aggression and cognition. It is also concluded that additional research is needed to determine why some intersex patients assigned and reared as girls are not successful in this identity and role.