Vault101 said:
how is being gay any different from people who want to have sex with dogs?
Seriously?
On the topic at hand.
We simply don't know.
Thus, we can't draw any differences or similarities to other conditions.
It's expected to be a disorder in the brain.
The whole "Different sex brain" thing is completely non-sense, it basically just means it shows up on a brain scan. Much in the same way depression or other mental ailments display. The idea "it's a woman's/man's brain in there!" is also completely untrue, the brain still overwhelming resembles the sex of the person in question.
I regards to "Why it'd make you want to change your gender", I can only really draw the following comparison, and I'm not even sure if it's accurate, so, do correct me if I'm wrong here.
Imagine your biggest insecurity. The thing you feel worst about yourself. Now imagine it's always there. Everyone can see it, nobody can ever not see the. You see it in the mirror, it's all you see. You hate it. It's completely irrational that you do, but, you do.
The feeling doesn't go away. It grows, and despite as accepting as people are, and as much they try to help, they cannot.