JMT wrote: To me, that isn't nature, it's psychiatric. I don't see it as much different than some guy thinking he is a bird and then getting feathers implanted all over his body.
South Park did it!

Well, almost.
You're right in that respect, it's a psychiatric condition, when your brain is one sex but your body is another. Only recently has technology caught up, in some respects, to the condition. Male-to-female sex changes are quite routine, and the engineering is getting very good, to the point where it is really just aesthetics. The bits aren't functional in the sense that a transgendered woman can have a baby or have sex without the aid of K-Y or whatever, but aesthetically it's almost there. 20 years from now it would not surprise me to see transgendered women who can conceive and give birth, and go through the motions of sexual intercourse without a tub of K-Y.
The only surefire way to find out if a woman is trans or not in about 50 years will be a genetic screening, and I expect in a century even that problem will be licked.
So basically the problem has always been there, and the sufferers have usually either had to subject themselves to hackjob surgeries and still not be happy, or suffer in silence and usually end up killing themselves.
Now, this is all male-to-female. Female to male is way behind due to the plumbing.