Hmm... I've heard of this before. I believe it occurs when the person has two underdeveloped sex organs (i.e. male and female) or has one that's more developed than the other. It's a genetic disorder, and the first problems would begin to form (though might not show up) while the fetus was still in the very early stages of development. You should look it up on Google... though Wikipedia has turned up some interesting results in the Women-Focused Support forums.

In all seriousness, though I'm not sure I remember the name of this disorder, it's now reparable fairly early on through plastic surgery, which is good news for those who have it.

~muse