Is homosexuality genetic?

[Drewbot]

I have heard people say that homosexuality is genetic.

However, based on evolution, wouldn't homosexuality as a trait have been lost generations ago, due to the low reproductive rate of homosexuals?

Is it generally accepted that homosexuality is a genetic trait?

If so, how is this trait passed on to the next generation at a rate that would allow the trait to continue?

 

[Mirrorglass]

I'm not certain whether it's been conclusively proven that homosexuality is genetic. However, it would seem reasonable to think there is a genetic tendency for homosexuality, as a percentage of all human populations is homosexual, despite cultural differences.

It is also fairly easy to theorize how homosexuality could be hereditary, though it takes some knowledge of game theory.

Basically, evolution doesn't always favour only those attributes that promote the survival of the individual, but also those that promote the survival of the entire community. This is called kin selection^WP. It is known that animals exhibit altruism, behaviors which don't necessarily result in passing on of genes, but improve the overall fitness of the group. The idea is fairly simple; from an evolutionary point of view, your brother or even your second cousin surviving means many of your genes will pass on, so behaviours that promote their survival are often favoured by natural selection.

So how does this relate to homosexuality? Well, basically, humans are extremely social animals. It is our capability for forming large and complicated societies that has allowed us to become the dominant mammal on the planet. But as I'm sure you've noticed, it takes a lot of work to maintain social relationships. Every day, we smile at each, exchange pleasantries, look each other in the eye.. a lot of things that aren't strictly necessary for survival, but help hold the society together. Many of these behaviours are universal to humans all over the world, and most higher mammals exhibit social behaviour as well. Homosexuality could also be interpreted as a form of social behaviour, and as a matter of fact a close relative of ours, the bonobo, actually exhibits homosexual behaviour. It serves several social functions, such as conflict resolution and reconcilitation.

Obviously the social function of homosexuality in humans would be more complex than that; we don't see men sixty-nining it out after a disagreement over a referee decision (at least not in the bars I frequent ). But there have been many instances of homosexuality throughout history, and quite often it's practiced by men and women who also engage in heterosexual relationships.

So, to sum it up, it's possible that homosexuality serves a social function that improves the overall fitness of the human race. To prove it does would be extremely difficult, but it's certainly a possible construct, and in my opinion does a good job of predicting the actual prevalence of homosexuality.

 

[HansMustermann]

In a MRI study they found that at least _some_ of the brain wiring of gay men seems to work like that of women, and viceversa. And that wasn't even for sex, but the fight or flight response.

Of course the question remains if that's genetic or not, or some hormone imbalance in the womb, or really, what the hey causes it?

But at any rate that kind of wiring between the lobes is already done in the womb and I'm not aware of anything one can do later to change it. The net effect is that some people are born wired as the opposite gender. (Though enculturation means they won't fully act or think like a woman by the time they're adults, mind you.) It's not a matter of choice, it's not a matter of influence, it's not a matter of being corrupted by some gays in the neighbourhood, it's simply being born that way. Regardless of whether it's genetic or what, they just are born that way.

Which also means that they're not going to corrupt or set a bad example for anyone who isn't born with the wrong wiring pattern. Genetic or otherwise those other people are already born with the wiring saying what gender they'll be attracted to. They're not gonna become gay just because they see a gay couple being all fabulous in the neigbourhood.

So IMHO the best we can do either way is basically to accept it and let them be.

 

[Longfellow]

Does not belong here

Wouldn't this thread be better off in the Science, Mathematics, Medicine, and Technology section of the forum?

 

[Skeptic Ginger]

You cannot assume homosexuals don't reproduce. And there are at least a couple identical twin pairs where one is gay and one isn't. The hypothesis being hormone exposure in utero may trigger homosexuality.

A pair of monozygotic twins discordant for homosexuality: Sex-dimorphic behavior and penile volume responses

The homosexual twin showed the effeminacy syndrome. Aspects of the syndrome can be induced in mammals by altering their hormonal environment during some critical period in their intrauterine development. Discordance for homosexuality in identical twins could be due to one's being exposed to a different hormonal level during such a critical period.

There may be multiple causes and/or the cause may be multifactorial.

I think we can say for certain the evidence is pretty strong it is a physical and not a learned drive.

 

[IMST]

My understanding of the identical twin studies on it, however, was that it showed far more correlation than did handedness. I'm quite confident that any final determination will end up being part genetic part not.

 

[Baylor]

Anecdotally, I've heard that as a woman has more children, the chances of the child being gay go up drastically, much like Down's Syndrome. I'ven't seen any studies, just anecdotal evidence.

 

[Sword_Of_Truth]

Wouldn't this thread be better off in the Science, Mathematics, Medicine, and Technology section of the forum?

The philosophical ramifications are far bigger than the scientific ones.

Like what happens if they find a "gay gene" and develop a pre-natal screening test?

Are we prepared to continue protecting Roe v. Wade as lazy parents unwilling to deal the additional challenges a gay child brings start annihilating the next generation of the gay community in utero?

What if, in a slightly more optimistic scenario, someone develops a gene therapy that eliminates the anomaly? Members of the gay community almost invariably describe being at war with themselves and often the rest of the world over their identity in their youth. What if you could offer them a pill which could make all the fear, pain, confusion and anxiety all go away? How many gays would take the pill? Would the gay community effectively self-annihilate?

Is society prepared to have the oft-maligned "religious right" lose a critical battle (the nuture v. nature debate) only to have them also win the war by default?

What would the ramifications be for those that remain? How would they continue their political and social objectives with the silencing of so many friends and allies? Would the gains of the preceding decades remain in place, or would they enter a new "Gay Dark Age"? An age of oppression for the gay community that differs from previous ones only in the existence of a medicinal escape hatch?

 

[Complexity]

Some people have been aborting gays for a very long time.

Not having the advantage of genetic testing, they simply waited until the kids grew up enough to be suspected of being gay. Some were killed outright, while others were only partially destroyed.

We non-straight people will be around for the duration.

 

[Tatyana]

It isn't genetic in the sense that there is a 'gay gene', but as it relates to the expression of the chromosomes and various genes on the chromosomes during foetal development, it is genetic.

Sexual differentiation is far more complicated than XY = boy, XX = girl.

There are a phenomenal number of things that can happen with enzymes required for our sexual differentiation.

The enzymes may not work, for example, alpha-5-reductase deficiency (baby born looking like little girl, turns into boy at puberty) or the enzyme may work too much, for example, CAH, congenital adrenal hyperplasia (baby girl exposed to too high levels of testosterone from adrenal glands during development, therefore born with ambiguous genitalia or somewhat male looking genitalia).

There is a child born intersex or with ambiguous genitalia approximately one in every three thousand live births.

Homosexuality is a very normal type of expression of the phenomenal range of sexual expression that can happen in humans.

 

[rjh01]

It could be that if you have certain genes then you have certain advantages. However if you have a minor variation then you homosexual.

 

[KingMerv00]

Are we prepared to continue protecting Roe v. Wade as lazy parents unwilling to deal the additional challenges a gay child brings start annihilating the next generation of the gay community in utero?

I am.

Aborting a fetus because of potential homosexuality is disgusting in the same way KKK rallies are disgusting. Both should be legally protected.

 

[Robin]

What if, in a slightly more optimistic scenario, someone develops a gene therapy that eliminates the anomaly? Members of the gay community almost invariably describe being at war with themselves and often the rest of the world over their identity in their youth. What if you could offer them a pill which could make all the fear, pain, confusion and anxiety all go away?

What if, in an even more optimistic scenario, someone develops a gene therapy that eliminates bigotry.

If you could offer the bigots a pill to take the bigotry away then that would also make the fear, pain, confusion and anxiety for the gay community go away.

Would the bigot community take the pill and self-improve?

 

[Robin]

It could be that if you have certain genes then you have certain advantages. However if you have a minor variation then you homosexual.

It could be, for example, that having a certain gene means a higher likelihood of gay preferences arising and that primitive communities having this mutation had a better chance at survival since fewer members of their community were reproducing and there was a lower pressure on resources.

These communities would also have a higher percentage of adults to children providing more manpower for defence and food gathering.

Only a conjecture.

 

[bookitty]

What if, in an even more optimistic scenario, someone develops a gene therapy that eliminates bigotry.

If you could offer the bigots a pill to take the bigotry away then that would also make the fear, pain, confusion and anxiety for the gay community go away.

Would the bigot community take the pill and self-improve?

This.

 

[Speed of Light]

It's only really in the last generation or two, that those with a potential (weakness?) have been encouraged (allowed?) to express their homosexuality.

So evolution has not yet had a chance to eliminate this trait.

It might be that in a very few generations, homosexuality will be drastically reduced

 

[Mirrorglass]

It's only really in the last generation or two, that those with a potential (weakness?) have been encouraged (allowed?) to express their homosexuality.

So evolution has not yet had a chance to eliminate this trait.

It might be that in a very few generations, homosexuality will be drastically reduced

Seems unlikely. It's not like homosexuality has always been considered wrong by everyone; that's a fairly recent phenomenon mostly rooted in abrahamic religions. Many cultures throughout history have accepted homosexuality, without it ever dying out.

 

[Tatyana]

It's only really in the last generation or two, that those with a potential (weakness?) have been encouraged (allowed?) to express their homosexuality.

So evolution has not yet had a chance to eliminate this trait.

It might be that in a very few generations, homosexuality will be drastically reduced

I would suggest you read some ancient Greek, Roman and Persian history.

Actually, investigate any other world history beyond the modern Western view.

 

[Sword_Of_Truth]

What if, in an even more optimistic scenario, someone develops a gene therapy that eliminates bigotry.

If you could offer the bigots a pill to take the bigotry away then that would also make the fear, pain, confusion and anxiety for the gay community go away.

Would the bigot community take the pill and self-improve?

Which of the two is more likely to be developed first?

And would an "anti-bigotry pill" deal with the mathematical issues?

We spend enormous amounts of time and energy searching for "Mr./Miss Right" (or Mr./Miss Right-Now). A heterosexual will have a field of candidates consisting of 45% to 49% of the population (those members of the opposite gender who are sufficiently straight to make such coupling likely). The field of potential mating candidates for homosexual is at most 1/10th what it is for a heterosexual.

Homosexuality is unlikely to ever out-sell heterosexuality. Even in the most permissive and tolerant societies, the development of a "straightening out pill" will be bad news for the gay community.

 

[Shrike]

My wife's grandfather was gay. Her brother is gay. Judging from this pool, gayness is genetic, but it skips a generation I'll get back to you when I have grandchildren.

But seriously, granddad was victim of the abrahamic religions. By the time he came out of the closet, my mother-in-law was 15 and he had produced 5 children. So if it is genetic, there's been plenty of opportunity in the last couple of hundred years to pass it along.
And yeah, in ancient times homosexuality was way more common then it is now.