Although people have long used the word "hermaphrodite" to describe those with both male and female anatomical characteristics, it's a misleading idea. Today, the term for people with this condition is intersexed. Intersexed people don't have both male and female genitalia, but typically have some features of each. There is a wide range of variations among intersexed people.
Some intersexed people are known as true gonadal intersexed. They might be genetically male (XY) or female (XX) but have one ovary and one testicle or a single gonad with both testicular and ovarian tissue in it. Externally, these people might have clearly male genitalia, clearly female genitalia or ambiguous genitalia. The cause of this type of intersex is unknown.
XY intersex describes a person who has male chromosomes but genitalia that is atypical, ambiguous or female. Testes may be present, missing or abnormal. The most common cause of XY intersex is a problem with processing male hormones, known as androgen insensitivity syndrome (AIS).
A person who is XX intersexed usually has the internal genitalia of a female, but the external genitalia appears to be male. She may have a large, penis-like clitoris and fused labia. Most people with this condition have congenital adrenal hyperplasia, a disorder in which the adrenal gland doesn't produce cortisol or aldosterone, resulting in higher levels of the male hormone androgen. People with this condition may have been exposed to high levels of male hormones while in the womb or may be deficient in aromatase, an enzyme that converts male hormones to female hormones. XX children with the latter may start to take on more male characteristics at puberty.
In the next section, we'll look at a condition that is sometimes related to intersex: micropenis.