Definition of Gender identity disorder:

Gender identity disorder is a conflict between a person's actual physical gender and the one they actually identify him or herself as. For example, a person identified as a boy may actually feel and act like a girl.

See also: Intersex

Causes, incidence, and risk factors:

People with gender identity disorder may act and present themselves as members of the opposite sex. The disorder may affect:

• Choice of sexual partners
• Display of feminine or masculine mannerisms, behavior, and dress
• Self-concept

Gender identity disorder is not the same as homosexuality.

Identity issues can occur in many situations and appear in different ways. For example, some people with normal genitalia and sexual characteristics (such as breasts) of one gender privately identify more with the other gender.

Some people may cross-dress, and some may seek sex-change surgery. Others are born with ambiguous genitalia, which can raise identity issues.

The cause is unknown, but hormones in the womb, genes, and environmental factors (such as parenting) may be involved. The rare disorder may occur in children or adults.