Pixie
Just to clarify, when I said "black or white", I meant in terms of thinking of only two difinitive answers, rather than the many variables that need to be considered in these cases, no intention towards bringing race into the whole discussion.
Anyway, onto your questions.
1. Medically, of course there is. I'm not knowledgeable enough about transexual issues to know whether there are physical/hormonal issues with genuine Trans folk, or whether they should be classed as mental issues like APG mentions. Some people are born with disabilities, a tint number are born hermaphrodite. Given that, it's completely feasable that some could be born the wrong gender.
2. No, because unlike Transexuality, there is no possible medical condition behind race. Any attempt to identify as a different race is entirely down to personal desire, or as previously mentioned, mental illness.