Offtop:
Queenie and Cools techniquely you are both right. I'm Bisexual 
The Unforgiven is actually right on the mark. A person's chromosomal sex (xx, xy, xxy, ect.) does not necessarily translate into xx=female or xy=male. And to further the point, there is actually
scientific evidence that in Transsexuals there is a difference between the sex of their brain and the sex of their genitals. I have the lovely Ducth to thank for that bit of research, they did a study of MtF's and found that their brains were identical to those of biological females and the same goes for FtMs.
Gender is not dependent on biologicalo sex anyway
Talyubittu, the actual definitition of gender (lifted directly from all of my Psychology books) is a persons emotional, cultural and cognitive understanding of whether they are male or female. It has nothing to with biology. Sex however has everything to with biology. Gender and sex do not always match.
In terms of sex, you actually have two; Chromosomal Sex and Endocinological sex. The latter deals with your hormone levels. Are your levels of Estrogen and Testosterone (everyone has both) in the male range (more T than E) or in the female range (more E than T)? It's actually quite easily change through IntraMuscular injections of the opposite sex's main hormore. Once you change the body's chemistry there is no clear difference between a trans person and a non-transperson, except for their genitalia which is a very small part of the equation as I said before.