Did you know there are animals and insects that are half-male, half-female? I'm not talking about male seahorses that carry their young in a pouch or frogs that can gender mutate. Here's an article about creatures that have both male cells and female cells in their bodies, and exhibit a "split" of both traits on the outside.
Being a bearded lady I can't help but be interested in this kind of thing, even though it doesn't occur in humans. Sure, people are born with both sets of gender characteristics to varying degrees, but we can not be born with one side physically female and the other side male, the way birds and insects can. Fascinating! (Or am I just a real big nerd?)