Female pseudo-hermaphrodites occur when the internal organs are female but the outer genitals are masculinized. For example, the labia may be semi-fused (or closed), and the clitoris enlarged, looking like a smaller version of a penis. This can occur when an excess of male hormones interacts with the fetus.
The most common cause of female pseudo-hermaphrodites is the disorder Congenital Adrenal Hyperplasia (CAH). This is when the adrenal glands overproduce testosterone. Another cause is when the mother takes or encounters male hormones such as testosterone.
Male pseudo-hermaphrodites occur when there are internal testes (normally in the abdominal area) and the outer genitals are either incompletely formed, as an extremely short penis, or even, formed more closely to those related to a female’s genitalia. The vagina may be short and not wholly developed.