Gruntled - so you know you are a woman because you like stereotypical, traditional 'feminine' things? Make up, the colour pink, dolls, ballet etc.?
What if you liked football, short hair, trousers, running around getting dirty, and shouting? Does that make you a man? Or does that just make you a woman who likes traditionally more masculine pursuits?
Because that is the crux, isn't it. You are born male or female. Some transgender people are what I still think of as transsexual - so utterly disgusted with the outward appearance of their bodies because they don't match the way they feel, that they will do anything to change it.
As opposed to a lot of transgender people now, who seem to equate 'I always knew I was a girl because I liked Barbies and wearing skirts' as 'I am therefore Woman'.