They do? Never had that desire...
I'm to lazy to read a 104 pages so i'm just going to state my own oppinion and hope what i'm about to say isn't said a million times already...
No homosexuality is not a choice, homosexuality is nothing new either... It has been around since the beginning of time and it is a natural thing...
Their are homosexual animals, and there are plenty of ancient gay or bisexual people. During ancient greece for instance it was something completly normal to have sexual relations with both man and woman, you probably all know Alexander the great, he is considered a brilliant general and fighter and a great leader.
He was both bisexual and in love with his mother, this guy wouldn't have been as popular by modern standards, but you can hardly deny the great things he has done (threw wars I mean). So that gays can not fight is absolute bullshit, not only can they fight. A guy that sleeps with other guys is one of the greatest generals in history if not the greatest.
Back to the thing i was talking about before..
If homosexuality was something unnatural then there would not be gay animals, unless you wish to claim that animals are against nature?
If homosexuality was a choice why would people ever make that choice, one of my best friends is a lesbian... You woudln't believe the hard time she had when she had to tell her parents she was gay, she told me first... I spend weeks trying to talk her into telling it, comforting her, telling her people would accept her for what she was. She would never have been gay if it was a choice. Very few people would be, its something completly natural that you have no control over what so ever.