Intersex is a term used to describe a living organism born with external sexual characteristics that have attributes of both sexes. The internal and external sex organs are neither exclusively male nor exclusively female. Defining the sex of an intersex infant may be ambiguous and the causes are not fully understood. Sex assignment is a controversial issue, and standards are not concrete. In some medical circles, a fixed measurement determines whether external sex organs are male or female.
Intersex causes examination of the assumption that a Y chromosome makes a person a boy or a man and the lack of a Y chromosome makes a person a girl or a woman. The term may include people with androgen insensitivity syndrome, Kleinfelter syndrome, or congenital adrenal hyperplasia.