Ever wonder what makes you, you? What makes  man, a man, a woman a woman? Genes? Hormones? God? 

This article in the Washington Post on gender dysphoria describes a child's struggle with her identity as a girl. Literally from age two this "girl" demanded to be a boy. Simply said to her mom, something went wrong in your belly, I'm a boy. Ultimately the parents allowed their child to become a boy called Tyler. The change was instantaneous. A difficult, tantrum prone child became a happy go lucky, high energy boy.

My first experience with the blurring of sexual identity was as a medical resident when I met a patient with Testicular Feminization Syndrome. She was quite beautiful and extremely feminine which I found out is the norm in this syndrome. Her medical problem was amenorrhoea. She never had a period.

The essence of her problem? She was genetically male, born with testes, inside the abdomen, but on the outside physically female. Traditionally these women were told a simplified version of reality - they would not be able to have children. Nowadays, they're told everything leading frequently to a real and understandable identity crisis. Keep in mind these women look and are women in all senses except they don't have a uterus and are genetically male. In case you're wondering they do have a vagina and their sex life is normal apart from the fact they can't have children. 

Confused yet? My point is biology and genes only partly decide your destiny. Many things intervene. The take home message is simple, you may think your biology or genes makes you fat or prone to over drink or whatever and they may but you can change it. It's not written in stone.