Well... you seem to spend a lot of time with this, and I don't. But from what I understand the whole chromosome thing is "science". So.. I have an X and a Y... and girls have an X and an X. That's basic, right? And then there are other things that happen... Have you ever seen a male calico cat? I haven't. But I know such things happen. So talk to me about "science". I love to hear from the ignorati.