Only gays and lesbians, please: what do you think of this philosophy?

I sincerely believe that people are born gay. I have known all my life that I was attracted to members of the same gender. I didn't wake up one morning and say today I am going to be gay. I have just always been gay. However, I do believe that something can traumatize a person to the extent that it does affect their sexuality. This might be the situation with your wife's brother.