I study gender development, and am particularly interested in how prenatal influences (e.g., gonadal hormones) interact with postnatal experience to shape brain development and behaviour. My current research programme includes studies of individuals with disorders of sex development (formerly called intersex conditions), as well as healthy individuals for whom we have measures of prenatal hormones. Behavioural outcomes of interest include gender identity, sexual orientation, aggression, empathy, mood, sex-typical interests in childhood (e.g., toy preferences) and adulthood, and clinical syndromes that show sex differences. I also study infants, so that we can identify sex differences as they emerge early in life and examine their relationship to prenatal hormones and postnatal socialiazation. In addition, I am interested in the neural and cognitive mechanisms related to behavioural changes in these areas, as well as in animal models of human behavior.