Okay, I've written in the past about Caster Semenya and how an apparently black and white issue, your sex (male/female), can be anything but clear. In this case there are clearly understood genetic and biologic factors that can make it extremely difficult to determine the sex of an individual and can even lead to the conclusion that a genetically male person is a female.
Now I see a Dr. Oz show that featured a teenager who was born female but has always felt that she was a male. She had a mastectomy and started taking hormone blockers when she started to menstruate. She looks, sounds, and dresses like a boy and psychologically seems to believe quite strongly that she is a he.
They also had a little boy, maybe 4 years old, that has always believed that he is a girl. He is now a bubbling, happy, cute little girl that just happens to have a penis and dress and act like a girl. Her mother talked about all of the psychological problems this child had as he was forced to dress and act like a boy and how all of those problems have resolved now that they allow him to be a girl.
This mismatch between a person's genetic sex and the sex that they believe they are is called being transgendered. I have to admit knowing absolutely nothing about this so I'll be looking into it. But it makes me wonder about the separate issue of gender identity. Is there something biological going on inside the brain or that happened during prenatal development that caused this? Or is this a behavioral things, a mental illness that could be cured through therapy? With something this basic, I'm inclined to think that there is something biological going on.
Of course, if I was still religious this would be pretty easy to dismiss. Mormons in particular insist that gender and sex are one and the same and are an inherent spiritual attribute. Of course, since we can't investigate the spiritual plane, I guess we just have to take their word for that, as trustworthy as that is.