Is homosexuality genetic?

[EeneyMinnieMoe]

This is very anecdotal but I have a gay friend and, amazingly, he had a now late gay uncle, a lesbian cousin, a transsexual cousin and his father is a bisexual who lived with men before he met my friend's mother. And I think there are a few other people who are gay in his extended family!

That's a lot of gay in one family. A lot.

So I can believe it's genetic. In part, at least.

 

[Speed of Light]

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

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

I have to admit that I'm not expert on history.
It just seemed extremely logical that a trait which drastically reduces reproduction, which has more or less suddenly began to be expressed much more, would very soon reduce drastically by natural selection.

I'm not familiar enough with history to know if an analagous situation has ocurred before.

Possible differences might be that there is now more equality of wealth.
The media has powerfully altered the 'norms' relatively quickly, and even made it a 'sin' to criticise it. Did such a powerful pro-homosexuality exist in ancient Greece, throughout the whole population?
And did it last for enough generations to test if it would reduce in time?

I do not know the definitive answer to these questions, but I have to admit that I am a bit 'Skeptical' (funny me using that word!) that the past has disproved my theory - but I wait to be proven wrong (like any good skeptic!)

 

[Robin]

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

I don't think either is likely to be developed at all.

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

Of course - more people out in the open means a bigger field.

Homosexuality is unlikely to ever out-sell heterosexuality.

Nobody said it would, although American Christian conservatives appear to be terrified that it will. To hear them talk you would think that a single tele tubbie with a handbag might wipe out a generation of American heterosexuality.

Even in the most permissive and tolerant societies, the development of a "straightening out pill" will be bad news for the gay community.

It might in societies plagued by bigotry, but in more enlightened societies I can't see that. I have never encountered the "at war with themselves" gays you describe.

 

[Uncayimmy]

I have to admit that I'm not expert on history.
It just seemed extremely logical that a trait which drastically reduces reproduction, which has more or less suddenly began to be expressed much more, would very soon reduce drastically by natural selection.

I'm not familiar enough with history to know if an analagous situation has ocurred before.

Possible differences might be that there is now more equality of wealth.
The media has powerfully altered the 'norms' relatively quickly, and even made it a 'sin' to criticise it. Did such a powerful pro-homosexuality exist in ancient Greece, throughout the whole population?
And did it last for enough generations to test if it would reduce in time?

I do not know the definitive answer to these questions, but I have to admit that I am a bit 'Skeptical' (funny me using that word!) that the past has disproved my theory - but I wait to be proven wrong (like any good skeptic!)

You're making the assumption that homosexual men and women start out and remain exclusively homosexual all through their reproductive years. If that's the case and it's exclusively a single genetic component, then it would surely peter out (pardon the pun). The biological drive to reproduce is pretty strong, so it wouldn't take much to make babies. If 10% (roughly) of "heterosexual" men have sex with a man at some point, I would think the reverse would probably be true.

Human sexuality seems to be a continuum. What if there are other factors that come together (again, pardon the pun)? For example, a mule is a cross between a donkey and horse, yet we have plenty of mules. What if homosexuals are a cross between people with certain genetic components? I'm no expert in genetics, but it seems plausible. It's more plausible than a sheep/human hybrid.

 

[JFrankA]

You're making the assumption that homosexual men and women start out and remain exclusively homosexual all through their reproductive years. If that's the case and it's exclusively a single genetic component, then it would surely peter out (pardon the pun). The biological drive to reproduce is pretty strong, so it wouldn't take much to make babies. If 10% (roughly) of "heterosexual" men have sex with a man at some point, I would think the reverse would probably be true.

Human sexuality seems to be a continuum. What if there are other factors that come together (again, pardon the pun)? For example, a mule is a cross between a donkey and horse, yet we have plenty of mules. What if homosexuals are a cross between people with certain genetic components? I'm no expert in genetics, but it seems plausible. It's more plausible than a sheep/human hybrid.

I have to agree and you bring up a point that hasn't even been touched: bisexuality.

I know quite a few people who are bisexual, men and women, and I also know quite a few heterosexual and homosexual people who "switch" (for lack of a better word) depending on the circumstances and/or the people involved in those circumstances.

Personally, I tend to think it is both genetic and environmental, like anything else. I see someone's sexual preferences is the same thing as someone's preferences to a flavor of ice cream: some people love vanilla and that's all they eat, some would never ever eat vanilla, some people would only eat chocolate, in some circumstances some people would venture to enjoy Rocky Road, etc. I know that's oversimplifying it, but we are discussing someone's likes and dislikes, here. What makes a person enjoy vanilla but hate chocolate? Is it genetic?

Correct me if I'm wrong but is asking "Is homosexuality genetic?" the same thing as "Is preferring Rocky Roads ice cream over vanilla genetic?"

 

[HansMustermann]

The media has powerfully altered the 'norms' relatively quickly, and even made it a 'sin' to criticise it. Did such a powerful pro-homosexuality exist in ancient Greece, throughout the whole population?

I wouldn't say it was necessarily "pro-homosexuality" as such, but men and women were sufficiently segregated and social norms actually encouraged men to play among themselves, so to speak. Past some point attraction to a young male was actually fashionable and supposed to be a powerful driving factor, whether or not it actually resulted in actual homosexual sex.

But probably what goes even further is reading in an anthropology book about a tribe (sadly I no longer have the book to name that tribe) where homosexuality was apparently _mandatory_. Well, ok, bisexuality. Not only was intercourse with women limited to certain times and places, while with other men it was full time ok, but apparently boys were thought to be unable to produce their own seed until they acquire it orally from an older man. I'd guess it obviously didn't make itself extinct though, since it obviously lived long enough for an anthropologist to find it.

And while other tribes didn't go that far, there are enough where, for example, the shaman was supposed to be a transsexual.

And did it last for enough generations to test if it would reduce in time?

Is over a thousand years enough generations?

 

[Speed of Light]

You're making the assumption that homosexual men and women start out and remain exclusively homosexual all through their reproductive years.

I'm not making that assumption.
As you said yourself, it's a continuum -
These individuals will have less time to reproduce on average.
Therefore, in the population as a whole, they will produce less offspring
This is how natural selection works.
Evolution is usually caused by tiny differences in the reproductive capacity - but this is quite a major factor

What if there are other factors that come together (again, pardon the pun)? For example, a mule is a cross between a donkey and horse, yet we have plenty of mules. What if homosexuals are a cross between people with certain genetic components?

The reason that mules cannot repoduce is because it is unnatural.
Horses don't mate with donkeys in natural conditions.
It occurs only in very artificail conditions in captivity.
Mules are 'man-made'.
Only when there is none of their own species available - Their instinct to mate gets the better of them.

There is absolutely no evolutionary advantage in producing a genetic culdesac. Natural selection is the opposite of this

 

[McHrozni]

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

This should be a fairly safe area - at least one of the parents would have the gay gene anyway, so with an adequate explanation, they could see there is no need for their child to become gay, even if they fear it beyond all reason.

That aside, given that there are examples of identical twins who grew up together with one becoming gay and the other becoming straight (e.g. Kaczynski brothers), the chance of a gay gene as such existing is very low indeed. I think it's a combination of genes that are a risk factor, but the whole thing is also affected by environment (which is the other part of the reason why it seems to run in families) and simple random chance.

This would also explain why it can't be bred out of population. Latent genes will be passed on without anyone knowing and, with the right stimuli, will help develop an individual into a homosexual at some point.

McHrozni

 

[little grey rabbit]

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?

The construction of homosexuality as an exclusive orientation only began to develop, slowly, from the 1890s onwards.

Before that in the good old days the philosophy was "A woman for babies and a boy for pleasure"

Hence there is not necessarily an evolutionary advantage or disadvantage involved. I knew an immunology professor once, something of a crank, who insisted that studies show gay men had more children than straight men and it was just a case of overactive sex drives.

In which case it would be a positive advantage to have the genetic make-up tending towards homosexuality. But as I say he was a genial crank and I do not know if good studies show this.

 

[Speed of Light]

I wouldn't say it was necessarily "pro-homosexuality" as such, but men and women were sufficiently segregated and social norms actually encouraged men to play among themselves, so to speak. Past some point attraction to a young male was actually fashionable and supposed to be a powerful driving factor, whether or not it actually resulted in actual homosexual sex.

Is over a thousand years enough generations?

I'm not sure that this is analogous.
As in the creation of mules, this, as you have described it, is an artificially created scenario. When people are desperate, they do things that they wouldn't otherwise do.
Also, needing to comform to social norms, no matter how peculiar they are, is a very powerful survival instinct.
Look how poeple were conditioned in the last war in Germany.
Look at how people have been brainwashed to see super thin girls as attractive - which wasn't the case in the past.

Nowdays, those who supposedly have a natural inclination are encouraged to express it, but in that scenario, it looks as if there was pressure to comform, and they felt that they didn't have much choice.
People do comform!

So whether the natural inclination of those who would have, under 'free' circumstances become homosexual, was still intact, is perhaps not known

 

[Speed of Light]

This would also explain why it can't be bred out of population. Latent genes will be passed on without anyone knowing and, with the right stimuli, will help develop an individual into a homosexual at some point.

McHrozni

I thought I'd answered that.
What was only latent two generations ago, is now being expressed more - and presumeably might now begin to be bred out

 

[McHrozni]

I thought I'd answered that.
What was only latent two generations ago, is now being expressed more - and presumeably might now begin to be bred out

I wasn't asking you anything, I was giving my opinion on the matter

A genetic trait skipping two generations could be an example of what I was talking about, true

If the trait was significantly disadvantageous to the genetic survival individual - like it is in Iran, where people are executed for being homosexual - it may be bred out eventually. However, chances are that during this latent period of two generations, the genes have passed on to many more offspring than just the ones that exhibited the trait, who have in turn, passed it on to even more others. Some lines would die out, but others wouldn't and the population that carried the latent gene would in time grow larger again. It would take dozens of generations of extremely strict anti-gay policies to have any hope of breeding it out of the population.

Furthermore, this is assuming the said "gay gene" is not a product of a relatively simple point mutation, in which case new "gay genes" are potentially formed with every conception, and the chance of eradicating that are approximately nil.

McHrozni

 

[HansMustermann]

I'm not sure that this is analogous.
As in the creation of mules, this, as you have described it, is an artificially created scenario. When people are desperate, they do things that they wouldn't otherwise do.
Also, needing to comform to social norms, no matter how peculiar they are, is a very powerful survival instinct.
Look how poeple were conditioned in the last war in Germany.
Look at how people have been brainwashed to see super thin girls as attractive - which wasn't the case in the past.

Nowdays, those who supposedly have a natural inclination are encouraged to express it, but in that scenario, it looks as if there was pressure to comform, and they felt that they didn't have much choice.
People do comform!

So whether the natural inclination of those who would have, under 'free' circumstances become homosexual, was still intact, is perhaps not known

I'm not sure how and under what circumstances you would envision that extinction of homosexuality. We have a full spectrum including, but not limited to,

- forbidden (Abrahamic religions)

- accepted (e.g., pre-christian Romans)

- encouraged / fashionable (e.g., Greeks)

- mandatory (e.g., that tribe I mentioned)

and various shades in between those points, like at various stages the Ottoman empire had it basically more like frowned upon in practice than hanging offense, or the Japanese, or various others.

There are enough tribes where there wasn't even any pressure to also make children with a woman, because pre-animal-husbandry most hadn't fully figured out why women get pregnant. It sounds hard to believe, but it's true. Children happened for a lot of tribes when the spirit of a child chose a woman to carry him/her in her womb, and sex was entirely tangential to that, or merely a helper ritual. (Sorta like lighting candles and incense before praying for a miracle. It might help, but you can also do without in a pinch.) So you could jolly well be gay full time and not even know that you're taking yourself out of the gene pool that way, hence have no reason to prevent that.

Sure, none is 100% identical to modern day Western Europe, or for that matter to each other. But it's quite the spectrum nevertheless. Take your pick of behaviour or attitude towards it, and some group out there will be close enough.

But I'm not seeing any of those having lost that "gene" as a result.

 

[little grey rabbit]

again, you need to be aware that homosexuality is at least in part a constructed identity.

 

[kuroyume0161]

again, you need to be aware that homosexuality is at least in part a constructed identity.

Not so sure about that. As soon as I hit puberty my inclination was for boys, not girls. It wasn't something that I chose or constructed. I didn't realize that I was gay until my twenties because the time and place in which I grew up was very white trash/religious. No construction there, just a lot of confusion and rejection.

 

[Speed of Light]

Not so sure about that. As soon as I hit puberty my inclination was for boys, not girls. It wasn't something that I chose or constructed. I didn't realize that I was gay until my twenties because the time and place in which I grew up was very white trash/religious. No construction there, just a lot of confusion and rejection.

'Construction' and conditioning are unconscious, so you wouldn't really see it happening. That is why conditioning is so strong.
It can sometimes take a lifetime to become aware and to overcome our conditioning. The fact that you brush aside the idea without apparently a second thought, seems to indicate that you haven't really become aware of that possibility

 

[little grey rabbit]

Not so sure about that. As soon as I hit puberty my inclination was for boys, not girls. It wasn't something that I chose or constructed. I didn't realize that I was gay until my twenties because the time and place in which I grew up was very white trash/religious. No construction there, just a lot of confusion and rejection.

None of which would have stopped you merrily having kids in a historical period where the idea of an exclusive homosexual identity did not exist.

 

[Cainkane1]

I read this once sometime ago. During evolution mammals at first were uninterested in sex until estreus. If a male animal exhibited sexual interest in other males then the dominant male who reproduced during the fertile times of a female would be less likely to consider a homosexual male to be a threat or rival to his harem. During unguarded moments the homosexual male could reproduce unnoticed by the male harem leader.

Evolution progresses and human females no longer go into estreus and hence the behaviour of gay humans remains same sex only.

This theory excludes female homosexuality although it seems to me that a female harem would benefit from certain attentions given by a female harem member. Estreus comes and the female homosexual behaviour ceases until after reproduction.

 

[Shadowdweller]

If the trait was significantly disadvantageous to the genetic survival individual - like it is in Iran, where people are executed for being homosexual - it may be bred out eventually. However, chances are that during this latent period of two generations, the genes have passed on to many more offspring than just the ones that exhibited the trait, who have in turn, passed it on to even more others.
McHrozni

Not quite. Natural Selection is not the entirety of evolution. Consider: Down's Syndrome and sickle-cell anemia both have notably deleterious effects, yet they persist. Why? Because our genetic code is subject to damage, replication error, and other forms of mutation. Particularly where the selective pressure against a particular trait is small, the incidence of that trait brought on by novel mutation may well exceed any possible decrease in reproductive rates exhibited by individuals who possess that trait.

Since nobody has yet brought it up, it should be noted that mutations in genes associated with pheromones or pheromone receptors in other mammals have been demonstrated to affect "sexual orientation".

http://www.nature.com/nature/journal/v448/n7157/abs/nature06089.html

 

[Speed of Light]

If the trait was significantly disadvantageous to the genetic survival individual - like it is in Iran, where people are executed for being homosexual - it may be bred out eventually.

With all due respect, I'm not sure that I follow your reasoning.
It is only when latent is actualised, that it will be bred out.
If homosexuality is banned, then it will just remain latent, and won't then die out

However, chances are that during this latent period of two generations, the genes have passed on to many more offspring than just the ones that exhibited the trait, who have in turn, passed it on to even more others. Some lines would die out, but others wouldn't and the population that carried the latent gene would in time grow larger again.

The best way to understand natural selection, is to think of it in statistical terms. It takes only a slight loss of reproductive capacity and the trait will become evolved out.
For example, if a sub-section of the population breeds even slightly less than the rest of the population over time., it is inevitable that this sub-section of the population will shrnk compared to the rest of the population.

That sub-section of the population which contains the latent homosexuality, which becomes expressed only under certain conditions, and as long as those conditions are sometimes fullfilled, will inevitably cause a shrinking of tha sub-section.
Because the latents will reproduce over time at a perhaps slightly lower rate than those without latents, the proportion of latents will inevitably decrease.
Natual selection is slow (perhaps) but sure

but others wouldn't and the population that carried the latent gene would in time grow larger again.

Only in so far as the whole population might increase, but the proportion of that population containing the latents will inevitably decrease over time as compared to the rest of the population, as its growth rate will be slightly lower due to a certain proportion of expressed latents

Of couse, if the whole climate of opinion in the country changed, then that would be different, but as long as the pro-homosexuality remains at its present level, then it might be that being evolved out is inevitable

It would take dozens of generations of extremely strict anti-gay policies to have any hope of breeding it out of the population.

As before, I'm at a loss to understand this idea.
Natural selection works in the opposite way.
It has to be expressed for it to be evolved out