How gay?

Fascinating article someone sent me today. As much as I don't really agree that science can explain everything about human life and behaviour, some conclusions are striking:

“If you can’t make a male attracted to other males by cutting off his penis, how strong could any psychosocial effect be?”

[...]
Whether women describe themselves as straight or lesbian, “Their sexual arousal seems to be relatively indiscriminate — they get aroused by both male and female images,” Dr. Bailey said. “I’m not even sure females have a sexual orientation. But they have sexual preferences. Women are very picky, and most choose to have sex with men.”
[...]
Sexual orientation, at least for men, seems to be settled before birth. “I think most of the scientists working on these questions are convinced that the antecedents of sexual orientation in males are happening early in life, probably before birth,” Dr. Breedlove said, “whereas for females, some are probably born to become gay, but clearly some get there quite late in life.”
[...]

Dr. Bailey believes that the systems for sexual orientation and arousal make men go out and find people to have sex with, whereas women are more focused on accepting or rejecting those who seek sex with them.

Similar differences between the sexes are seen by Marc Breedlove, a neuroscientist at Michigan State University. “Most males are quite stubborn in their ideas about which sex they want to pursue, while women seem more flexible,” he said.

[...]

A somewhat more straightforward clue to the origin of homosexuality is the fraternal birth order effect. Two Canadian researchers, Ray Blanchard and Anthony F. Bogaert, have shown that having older brothers substantially increases the chances that a man will be gay. Older sisters don’t count, nor does it matter whether the brothers are in the house when the boy is reared.

I do have a brother, so...