Why do some females have a penis?
This is due to hermaphroditism, or the newer term "intersex", which can be caused by many things. Often while still during gestation, the female is exposed to male hormones which cause them to develop external male genitals. The labia fuses and the clitoris enlarges to look like a penis. Often this is also due to chromosome disorders, in which a person has either more or fewer than 46 chromosomes, or in other words they are missing or have too many sex chromosomes.