>> It is no surprise that the male and female versions of the human brain operate in distinct patterns, despite the heavy influence of culture. The male brain is sexually oriented toward women as an object of desire. The most direct evidence comes from a handful of cases, some of them circumcision accidents, in which boy babies have lost their penises and been reared as female. Despite every social inducement to the opposite, they grow up desiring women as partners, not men.

>> “If you can’t make a male attracted to other males by cutting off his penis, how strong could any psychosocial effect be?” said J. Michael Bailey, an expert on sexual orientation at Northwestern University.

http://www.nytimes.com/2007/04/10/health/10gene.html?8dpc=&adxnnl=1&adxnnlx=1176180084-2b80Oavz2Sik19NFTiq4rg

Good question. There's more ....

>> In experiments in which subjects are shown photographs of desirable men or women, straight men are aroused by women, gay men by men.

>> Such experiments do not show the same clear divide with women. 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.”

Breedlove? What a great name for a sex scientist. He was obviously born to be one.

I would be curious if sexuality was selected if a species could survive? Sexuality being a choice makes very little sense.

sexuality <> breeding.

sexuality = breeding for 99.9% of the animal kingdom, and for humans as well no matter how much abstraction we try to pile atop it.

6.5 billion people = we need more gays.

not if you see sexuality as a bonding ritual. 

any pleasurable/positive physical contact between animals which does or does not result in an egg being inseminated could be considered "sexuality" by this (admittedly perhaps overly broad) definition.

sexuality != breeding.

Sexuality != anything goes.

As the brain's neural structures are laid down long before culture gets its paws on them. Which doesn't mean culture has no impact -- during Victorian times, there was a phenomenon of young men swooning in ecstasy at the sight of a white handkerchief.

But the framework is built, and culture just injects some spice into it.

Neat.  So male gays are born that way, but for female gays it's a choice.

I'm not so sure I'm copacetic with that.

More goodies for the PC mind ...

> Several profound consequences follow from the fact that men have only one copy of the many X-related brain genes and women two. One is that many neurological diseases are more common in men because women are unlikely to suffer mutations in both copies of a gene.

Another is that men, as a group, “will have more variable brain phenotypes,” Dr. Arnold writes, because women’s second copy of every gene dampens the effects of mutations that arise in the other.

Greater male variance means that although average IQ is identical in men and women, there are fewer average men and more at both extremes.

This stuff isn't exactly shocking Strawberry.  It might get the PC fanatic worked up, but that sort of person starts off in a pretty high state of worked up before they get out of bed.  Hell, even their alarm clock is a symbol of oppression (mine is more something for the cat to step on while he climbs in the window, and sometimes a target for a carefully flung pillow).  Besides, the animal is what it is.  Genes don't care much for political correctness.

All women are bisexual then?

Where the hell's my threesome?

And the flying car too.

It stacks up, as far as I can tell. Just about every woman I've known that I was able to really find about is aroused by women, or images of women, as much or even more than men. Sometimes almost ridiculously so. Yet most choose not to have sex with women.

Men have more money.