From what I learned about sexuality its that gays are born that way because they have an under developed portion of the brain called the Hypothalamus.

Why do some babies have an under developed Hypothalamus and some don't is the big question. Could it be baby formula vs Human milk, chemicals in the environment, vaccines or poor diet?

Hard to say but no one is focused on what main stream science already knows about human sexuality.

Sexual behavior is influenced by the hypothalamus. It stimulates the pituitary gland to release the sex hormones. When levels of those hormones falls, so does sexual desire.

http://www.cerebromente.org.br/n03/mente/hormones_i.htm

I think Dr. Joel Wallach explains it best.