The bottom line is no one actually knows, they do not know why a male wants to dress in woman's clothes, nor do they know why some people are born in the wrong body. The medical and scientific community has theories, but not facts. Perhaps in the future when they know more about our brains they will discover exactly why and today's theories may well prove to be correct or not.
We have placed labels on the various gender types and over history these have changed and will more than likely change further. Psychs and the like are all basing their opinions on their interpretation of the combined knowledge base to date.
