As to being geneticly made up to be gay.....I don't know. My mom thinks being gay is because of "distant" fathers. She says that my dad wasn't always interested in what my brother was doing. He wasn't a super athlete, although he is in so much better shape than I am(he is a big work out freak), wasn't really into hunting, just birds, and wasn't really into guns, unlike me. Was it because of my dad, I don't know. My dad is so proud of my brother now, you can't believe it. At the recent funeral of my grandmother, my dad introduced us to everyone, saying this is my son Jim, and this is my son Jeff, the doctor.
As for genetics, I remember my brother always the quiet, shy guy. When he was little, he wanted to be a witch for Halloween. He liked to play dress-up. We played guns, fished, hunted, but socially he like to hang out with the girls in middle school. In high school, he had lots of friends, girls, guys; they all hung out together. He had several very attractive, popular girlfriends. One serious enough to even follow him to medical school, but he never seemed that interested in them. Now, I think he already knew he was gay, but wanted to be straight. He broke down one day(according to my mom) telling her that if he told her why he was upset, she would hate him. She told him it was ok, and that she still loved him. I feel bad because my wife and I used to ask him all the time when he was going to get married, or if he had been out with anyone lately. He always said work was too demanding right now, and that he didn't have time to meet anyone. I'll bet that hurt. I'm sure he was afraid of what I would say.
So, I just don't know. Nature or Nurture? Maybe a little of both? Here's the last little bit of weirdness for ya......My dad's sister is gay. One heck of an athlete. She never got any attention as a kid because my dad and my uncle were super star athletes in school(so the story is told by relatives). She almost made the Olympic team in 80'. Lots of testosterone in that family. No one in that family, including my dad has ever acknowledged it. She and her friend come out to see my dad all the time.
BTW, As for not wanting to talk about his relationship with his friend. I want to ignore it, but I really haven't. I offered to pick "them" up at the airport and drive them to my mom's if they flew in for Christmas. I just don't want to talk about his sex life. His friend is anything but "gay" looking. He is about 6'3" 210, and built like a brick $hit house. Very down to earth, loves shooting, and riding motorcycles. Before I knew, I would never have thought he could be gay. Pretty cool guy, really.
Well, you guys can make up your own minds. I just don't think someone decides to be gay. Maybe some nurture, and some nature contributes to it.