theyeti

Genetic linkage establishes a genetic basis. If it is highly rare, like hemophilia, then it doesn't require an evolutionary explanation. We expect that natural selection will weed the alelle out, but since it's recesive, it persists at a very small frequency. As for cystic fibrosis, it is also rare and also confers resistance to Cholera in the heterozygous state. The evolutionary explanation for its persistance is roughly the same as that for sickle cell anemia. If homosexuality were as rare as most genetic diseases, or were not known to have any genetic component, then it could be ignored in evolutionary terms. But this is not the case.

theyeti

theyeti

Not identical, just more likely to be similar. The identical twin of a homosexual is more likely to be a homosexual himself, even if raised apart. This is the basis for finding that homosexuality is heritable. Just do a PubMed search.

theyeti

Pandora

One thing that I was wondering, having read through this thread – but I’m not sure how much I’m going off at a tangent, have any studies been carried out into creativity and homosexuality?

As a designer I have found that a very large number of my male co-workers and co-students were homosexual.

At first I thought it was probably because the “art” world tends to be more accepting of people’s differences, but in my experience these men were for the most part exceptionally talented – if they were merely there because they felt comfortable, surely they would have been more mediocre. I also noticed a distinct lack of lesbians.

Oolon Colluphid

This is off the cuff, I'll check, but, wasn't it twin studies that helped establish a genetic link in the first place? At least, a strong correlation?

IIRC from Ridley’s Red Queen, homosexuality is basically caused by two bursts of hormones, one in the womb and one at puberty. Whether the first counts as genes or environment is a question of semantics , but the second has an environmental component. As usual with genes, they set proclivities, which in interaction with the environment may or may not produce certain traits.

Gays are always going on about how they 'always knew', or 'always felt different'. Frequently despite the environment. 'Tain't determined, but nor is it purely environmental. Mostly towards the determined end of the scale.

[Edited to add: Not that the environment may be any less deterministic...]

Cheers, Oolon

[ January 28, 2002: Message edited by: Oolon Colluphid ]</p>

theyeti

But none of those things confer a disadvantage (except possibly eating dookie). The odd thing about homosexuality is not so much the interest for the same sex, it's the disinterest for the opposite sex. Rick, you can't just pull any old human behavior out of a hat and expect it to be analagous here.

Would you or would you not agree that these behaviors are genetically determined? Saying that a human doesn't do these things is just saying that a human is a different species.

I would say that these behaviors are, in part, genetically determined. Religiosity has been shown to be heritable, though the specific religion one adheres to is learned.

theyeti

Oolon Colluphid

Reading MortalWombat’s above post again reminded me: the question is not so much about why is there homosexual activity, but why are a small proportion of people drawn to it exclusively. Bonobos, for instance, will hump anything vaguely chimp-shaped. I gather that homosexual behaviour is quite widespread in mammals.

I suspect MortalWombat had most of the answer a page back. Humans are highly sexed, second only (and debatably) to bonobos. Sometimes gays sleep with women. Since there is a genetic component, there’s no impediment to it being passed on. But it clearly wouldn’t become the dominant variety of behaviour.

Dr Rick, you seem to be arguing that no human behaviour has a genetic component. Is that right?

Oolon

Oolon Colluphid

Pandora, I’ve wondered this myself. Gays do tend to be drawn towards acting etc. (Source: my brother-in-law, an actor, has noted this substantial skew in the distribution.) I’d hypothesise (and let others do the confirmatory or refuting research ) that the answer might lie in the left, apparently more creative, hemisphere. That is, whatever the brain anatomy/chemistry changes are that cause homosexuality, they might be correlated to changes in the artistic bits of the brain.

Just a thought.

TTFN, Oolon

abe smith

Robochnermd: I don't have time to read all of this thread; but I am struck by some of you bland & unsubstantiated assertions here, variously: e.g. that identical twins do not demonstrate any [duplication, I forget the term} of homosexuality. That is if one twin evinces "homosexual" behaviour, does the other twin? The true stat answer seems to be, "sometimes". If you[as you appear to do} think that stats mean anything? Also, your intrepid assertion that "homosexuals " do not have children {I forget your exact words up-aloft} is dubitable in the extreme.... You"re probably defining "Homosexual" as MALE, according to the standard biassed pattern; { Is "bi-assed" some kind of naughty Freudian pun?.. Don't think so....] Some so-called "gay" males DO marry & DO have children ; and by the way, hey, "pater is always incertus", ya know? And certainly many so-called "lesbian" women DO have children. }

Dr Rick

There is considerable evidence to suggest that there is a genetic component to homosexuality, but the fact that it does not occur in most identical twins of homosexuals strongly argues that there is much more to this characteristic than just genetics, Genes may play a minor role and merely confer a predilection towards homosexuality. If human sexual preferences were just heritable traits, identical twins of homosexuals would all be homosexuals.

Theyeti, you are right about the cystic fibrosis gene

Dr Rick

Obviously, or you wouldn't have made all of these misrepresentations.

I did bother to actually read your post, and I still don't know what you are blabbering about.