A condition, sometimes called transsexualism, in which an individual develops a gender identity inconsistent with their anatomical and genetic sex.

Researchers have suggested that both early socialization and prenatal hormones may play an important role in the development of transsexuality. It is estimated that about 1 in 20,000 males and 1 in 50,000 females are transsexuals. Gender identity disorder generally begin to manifest between the ages of two and four, in which a child displays a preference for the clothing and typical activities of the opposite sex and also prefer playmates of the opposite sex. Young boys like to play house (assuming a female role), draw pictures...