Hi. I'm not a transsexual but I saw a documentary on Discovery Health ("I Am My Own Sister" -- I've seen this available several times since I saw it) that makes me think transsexualism may be due to a condition called chimerism. I don't know whether this has been discussed here yet, but wanted to post this because I know a lot of transsexuals still wonder if they're crazy. In chimerism, two separate eggs get fertilized and join before cell division. The individual this creates actually has two sets of DNA. They may appear perfectly normal but the "hidden" DNA resides in some, but not all, organs.
Hermaproditism is a form of chimerism. The documentary showed a child who had a black father and a white mother. The child was actually divided down the middle, black and male on one side, and white and female on the other. Each side had different DNA. They also featured two women whose childrens' DNA "proved" that they weren't the mothers' children, even thought the mothers knew very well that they had given birth to them. In both cases, extensive searching and biopsies finally revealed that in one them, one ovary was from the sister egg (which, if it hadn't merged with the other egg, would have developed as a fraternal twin); in the other, they found the "sister" DNA in her thyroid gland. They stopped searching once they had found it, so it probably existed in one of her ovaries too.
My theory is that transsexuals are chimeras -- merged male and female fertilized eggs. The body is one gender, but whatever part of the brain it is that determines what gender one feels is from the other egg. You're not crazy, or even weird. I suspect many more people are chimeras than know about it. If the DNA of the other egg ends up in your liver, you may never know. If it ends up in your "gender center", you'll know in spades.
I'm heterosexual, but 30 years ago I found myself attracted to both men and women. I (I'm a woman) tried having sex with a couple of women, but it made me feel like a man, and I hated it. I wasn't a man. My sexual identity was that I was a woman. That's why I believe there's a sexual identity center in the brain (or somewhere).
I've never seen the concept of chimerism put together with transsexualism in the medical literature, but that doesn't mean I'm wrong.
Good luck, everyone. I know it's a terrible struggle for you. I hope my theory gives you some relief.
ruby2zdy