Actually, though, the more older brothers a man has, the more likely he is to be gay: one explanation why male same-sex attraction is selected is to reduce procreative competition when there are more and more males. That's a take on primogeniture, in a way.

I think almost everyone believes environment has some impact on sexuality. With men, genes do seem to matter a whole bunch--perhaps more than initially expected.

greendyke--
For women, the sense is the complete opposite--genetic factors seem to be dwarfed by the environmental factors. The brain scan paper that you referenced nicely illustrated this. That isn't to say that female sexuality isn't an intrinsic trait. Just that factors other than genetics, like hormonal conditions in the womb, seem to be predominant.

*idiot!*

That's theory #1. I was so sad to find out this probably isn't true.

As for the scientific rational for why women are lexbians. The rational for womens sexuality is more fluid makes a lot of sense (not that there is anything wrong with it)

But maybe, JUST MAYBE, women are just more accustomed at putting up with bull shit and oppression throughout history than men. Perhaps men were more willing to come out of the closet with such destructive and intense consequences it intrigues the curiousity.

I mean scientists are humans too, what would you be more interested in studying? The men who are so sexually frustrated they come to forsake their family and fuck like rabbits, or the women who "discover their true feelings". Show me the female version of Larry Craig, then we'll talk.

You want a detailed breakdown? Take a moment and write a question to Dear science and I'll take the time.

In the meantime, you want some data? Why not read one of the dozen peer-reviewed scientific articles to which I linked in the post.

While I appreciate the advances that science makes, none of this should matter one iota relative to the social and political questions.

What if I don't have the gay gene, but want to experiment? What if I don't have the gay gene, but social factors have led me to choose homosexuality some or all of the time?

In the end, what we should care most about is the freedom to shape our lives, the freedom of self-determination.

If science is successful at identifying biological roots to homosexuality, there will certainly be those who will push for the vaccine or other methods of "curing" homosexuality. And, then, we'll be back at the gate of "freedom" arguing the point still.

So, let's just focus where the argument will take us anyway. :-)

You said that, for women "genetic factors seem to be dwarfed by the environmental factors" and then you said "that isn't to say that female sexuality isn't an intrinsic trait".

If lesbianism is primarily environmental, how can it be intrinsic or genetic?

at this point in scientific knowledge, there does not appear to be a strong link to a particular gene or genes with lesbianism. Furthermore, there doesn't not appear to be an obvious evolutionary mechanism (genetic based) as to why lesbianism occurs. The alternative hypothesis at this time, is environmental causes (development).

Mutations, at least productive mutations, are quite rare. Too rare to account for lesbians.

Not every intrinsic trait has to be genetic. Epigenetic changes, whether random or due to hormone exposure during pregnancy, can be lifelong and as unchangable as your genetics.

Epigenetics are changes in how the DNA is packaged, turning on and off genes. These changes can be copied from generation to generation of cells, persisting throughout life.

That isn't to say that female sexuality isn't an intrinsic trait. Just that factors other than genetics, like hormonal conditions in the womb, seem to be predominant.