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Study Finds No Single Genetic Cause of Same-Sex Sexual Behavior (scientificamerican.com)
63 points by yaa_minu 44 days ago | hide | past | web | favorite | 115 comments



Just because they can't pin something down to a single or low number of genes doesn't automatically mean there isn't a strong genetic determinant - it just means it might be spread among many factors, making any one factor hard to pinpoint.

From a high level view, the idea that something that is so critical to species survival, like a sex drive, isn't largely genetic determined seems rather unlikely.

I suspect the situation is something like height - this primer gives a good overview of properties of something that might be largely genetic but by many many factors. Also it covers the issue of rare exceptions, being different from the general rule.

https://ghr.nlm.nih.gov/primer/traits/height

Also note height is a continuous function not a binary state of tall or short - I suspect the same is here - this would easily explain, why some people feeling they were born that way, and others feel it's more a choice.


> From a high level view, the idea that something that is so critical to species survival, like a sex drive, isn't largely genetic determined seems rather unlikely.

Actually I found that surprising to hear. We have so many social processes that in many cases discourage and reduce sexual behavior.

Marriage works against the survival of the fittest you might get from sowing wild oats, but it's almost universal.

Homosexuality, indeed, is a discouragement to species survival (if I understand your meaning correctly). Yet you're claiming it is unlikely that it doesn't originate in genetics?

I don't know, I mean, I basically agree with your final statement - that we don't actually have a discrete variable here even if we largely see discrete behavior (since we tend to prefer long lasting relationships, so if you're F45-55M then you'll probably focus disproportionately on finding an M partner).

And what it means to be a guy or a girl is definitely not genetic. Most of our interaction with sexual beings is "pants on". And those pants, and the nature of our interactions, is hugely cultural determined.

And I think most people have the experience of being attracted to a person without engaging in any sex-seeking behavior with them. And many people seem to have experience of the reverse.

Given the cultural and experiential components of sexual attraction, I really don't think genetics need to be worth that much. Maybe there's some contribution, but it doesn't seem to have much scope, nor does it need it.


Marriage trades the advantage of sowing wild oats for the advantage of a pair of committed adults sticking around to raise the children to adulthood.

Survival of the fittest is useless if none make it to reproductive age (or the opportunity to reproduce), and humans are incapable of fending for themselves for at least the first couple of years of their lives. Simply reproducing with many is not a surefire way, and doesn't seem to be the optimal way, of guaranteeing that your genetic material endures.

Bret Weinstein has some interesting thoughts on the evolutionary merits of things like marriage and religion, I'd reccommend having a look at his work.


Another commenter has already dealt with marriage - it's much more complex that you think - just to add you appear to forget the womans point of view ( and genes ) entirely in you're assessment of the best strategy - where 'sow wild oats' obviously doesn't apply.

Also I'd have to say that one of the great successes of humans as a species is they are much more adaptable without genetic change than most - ie escaping our genetics is something to be acknowledged and celebrated not berated.

> Homosexuality, indeed, is a discouragement to species survival (if I understand your meaning correctly). Yet you're claiming it is unlikely that it doesn't originate in genetics?

I said the sex drive is likely largely genetic - note that there are two sexes! - women who are attracted generally to men and vice a versa - so both attractions would be encoded in the same genome - each by many factors. The question them becomes in any individual, which ones are switched on to what extent.

Genetic variation is a cornerstone of evolution, without it you can't genetically adapt or change.

Clearly sexual attraction involves the brain, which is one of the most adaptable organs in the body - so environment is very likely going to play a role - these things are not absolute.

Finally you seem to be under some illusion that the current state of humans is perfect adaption, rather than continuous work in progress against a constantly moving target.


Another point on attraction. Ideally you'd be attracted to a person that has the best 'genetic' fitness - ie ability to succeed. That's why things like symmetry are attractive ( a sign that development processes ran smoothly ).

However when it comes to things like predicting which body form will be most successful there isn't a single one as it depends on the environment. ie massive breasts and wide hips might be good for child rearing, but not very good for running. On the other hand in some situations a very large muscled man might be good - but not in a situation were food becomes scarce, or you need to be able to float.

ie there's isn't one form that fit's all niches - and so you'd expect there to be variation in body shape attraction as well.

So even putting aside the whole men/women different sexual attraction factors, even within one 'form' there will be significant variation.


> Homosexuality, indeed, is a discouragement to species survival

Maybe not. Homosexuality has been very widely observed in nature. [0] My understanding is that modern biologists tend to take the view that evolution is, for whatever reason, not acting to eliminate it.

There exist genetic disorders like cystic fibrosis which, it seems quite clear, have no evolutionary 'upside', but which nonetheless haven't been eliminated by natural selection.

I believe most modern biologists tend not to put homosexuality in the same bucket, simply on account of how widespread it seems to be in nature.

I have to say I don't understand Dawkins' idea that homosexuality might be a 'misfiring' of genes, contingent on modern human life, given that homosexual behaviour has been observed in other apes. [1] [0]

Annoyingly Wikipedia has very little to say on this interesting question. [2]

> Given the cultural and experiential components of sexual attraction, I really don't think genetics need to be worth that much. Maybe there's some contribution, but it doesn't seem to have much scope, nor does it need it.

I don't see how that figures. One would surely expect evolution to 'care' a great deal about mate-selection. That's how we have Fisherian runaways, after all. [3]

[0] https://en.wikipedia.org/wiki/Homosexual_behavior_in_animals

[1] https://www.youtube.com/watch?v=IDmQns78FR8

[2] https://en.wikipedia.org/wiki/Homosexuality#Evolutionary_per...

[3] https://en.wikipedia.org/wiki/Fisherian_runaway


The "born this way" aspect of gay activism is trending down, even apart from the lack of scientific evidence of a strong genetic component.

It was immensely useful during the gay rights movement, especially in the years preceding Obergefell, as a way to essentially persuade straight people, "This is not something I can control, so it's not something I can change, even if I wanted to." There was a de-emphasis on how sexual relationships typically develop -- through a serious of free, conscious choices to which sexual partners consent -- and instead an emphasis on sexual attraction itself, which often does not feel like a fully a conscious choice.

Now, I'm seeing more and more LGB people, especially those under 30, freely admit what had been considered an open secret: that many of those who insisted that they were "born this way" actually consider sexual orientation not to be immutable, but fluid, to various degrees. Whether one has conscious control over whom one finds attractive at any given time, of course, is another question, but for a time, evidence for sexual fluidity, especially within the queer community, was considered potentially damaging to the "born this way" efforts and de-emphasized or suppressed.

Post-Obergefell, more queer people seem to feel like they've gained enough legal and cultural ground that they can freely admit it, though. And some do in an almost defiant way, saying essentially, "So what if my sexual choices are free choices? If I choose to be gay, who's to say I shouldn't?"

That's a far cry from the prevailing narrative from just 10 or 15 years ago, when very few gay people would admit that they might have any conscious control over being gay.


I cannot understand how "born this way" could ever possibly not be true. Sure, today people can "decide" (or whatever) but why would anyone in their right mind decide to be gay like 200 years ago, and risk being ostracized from the community, being sexually unsatisfied and/or severely punished (including sterilization and/or death)?

(Obviously "fluidity" of sexuality does not preclude "born this way" - it could be that it's written in your genes that your sexuality would/will change throughout your life, similar to many people's libidos and/or hair color.)

Edit: on second thought, it's very possible that it could be random environmental influences (e.g. amount of... I don't know... drums + beech pollen ... the fetus is exposed to in the womb) - that could be pretty much orthogonal with genetics, while still leaving the person with "no choice". It's just that AFAIK most personality traits have a significant genetic component, either actually genetic or epigenetic [1].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739500/


Sexuality and attraction in general is an immensely complex topic. "Born this way" is not the only explanation. "Environmental factors" is not the only explanation. Rather it's a sum of it all, and for some they was just born that way, and for others they became that way because of environmental factors. For most is it all combined. See this study for more info https://www.sciencedaily.com/releases/2008/06/080628205430.h... (you'll have to find the source yourself, I do not have access to it).

The simple explanation is that we simply don't fully understand how sexual preferences form. But that should be a moot point on this because why should people care? You're a human, I'm a human ergo we have the same rights. End of story. I know that is not the world we live in sadly.

The underlying issue here is a matter of unity. People want to be with people like themselves, and consider sexuality a parameter in this. Obviously we need to change that, but it shouldn't matter one iota why some people are gay.


>why would anyone in their right mind decide to be gay like 200 years ago, and risk being ostracized from the community, being sexually unsatisfied and/or severely punished (including sterilization and/or death)?

I wish it were that simple, but unfortunately pedophilia still exists even though it fits all your criteria. Clearly some people adopt sexual behaviours even if it could lead them to a terrible outcome. Actually, some might do it specifically for that reason and the thrill of it.

You could make the same comment about religion, drugs, literature, politics etc... It's not rare for humans to adopt behaviors that put them at risk even if there are no obvious benefits. People routinely endanger themselves while doing kinky things. There probably are more kinks out there than there are genes in the human genome. There's clearly a large number of factors at play here, only some of them genetic.


This is assuming being gay is purely sexual, which, despite being called a sexual orientation, is misguided. There is more to attraction than sex, such as who you imagine you could be in a relationship with, who you develop feelings for, and who you love. In other words, while one may be aroused by certain sexual activities (kinks), no one develops a crush on someone because of a specific sexual activity.

Being gay isn't a kink, just as being straight isn't.

Straight people continued relationships despite being outlawed, which is the entire premise of Romeo and Juliet. Would you call Romeo and Juliet's relationship a kink?


>but why would anyone in their right mind decide to be gay like 200 years ago, and risk being ostracized from the community, being sexually unsatisfied and/or severely punished (including sterilization and/or death

Some people are way to powerful to be punished like Leonardo Da Vinci who apparently everyone knew was Homosexual but remained close to power because of his importance (mostly due to skill)

Even being terrorist or mass shooter is condemned by society but doesn't stop the determined ones.

Don't get me wrong, I am not saying being homosexual is like being a terrorist, just comparing the condemned part of the situation which used to be the case before.


I was very much 'born this way'. If I could somehow change it or be 'fluid' towards something else, I sure would. Anecdotal yes, but in these cases anecdotal is important because we're talking about personal experiences of individuals.

It might not be a single genetic element, it might be a combination. It might be epigenetic. It might be something during early development. But don't dismiss people who say they're born a certain way just because some other people supposedly said otherwise.


I completely believe you when you say you are “born this way.” I know many people in that boat. However, it still makes sense to me that only 8% of the variance in sexual orientation is determined by genetic factors. Some are “straighter” than others, some “gayer” than others, and some are more (or less) “born this way” than others.


We are only scratching the surface of genetics and epigenetics and no one in the industry pretends to have the tools to make statements like '8% of the variance in sexual orientation is determined by genetic factor'.

We know that e.g. dementia has a strong genetic component and have still failed to identify it despite knowing with certainty that component is there. We know faces are almost entirely determined by genetics but are still far off from being able to accurately predict a face from dna. We have a long way to go.

You're misappropriating studies that you don't understand to support a personal viewpoint that has no basis in the facts.


“8% of the variance in sexual orientation is determined by genetics” is literally a quote from the study. I don’t have a personal viewpoint one way or another. I’m literally just reading the facts as they’re presented and saying “many types of variance exist.”

Obviously some people choose to be gay, Cynthia Nixon for example, who got in huge hot water for saying that for her, being gay IS a choice. She was specifically not “born that way.” Others clearly are. It’s a spectrum. :)


Totally unrelated to this topic but what an interesting username choice.


Thank you. Praise Yeezus. :)


Uh, being fluid and “born this way” aren’t mutually exclusive. It’s definitely not that you wake up one day and decide now I’m gay. Maybe you wake up one day and decide today I’m going to act on it. And as it gets more acceptable in society more people are willing to act on things that previously they could decide not to act on. It’s a spectrum so some people can’t live without acting on, and some people can get by.

I’m “gay” and it’s not something I could change even if I wanted to. But I know that if someone who wasn’t the same sex came along and we got amazingly and there was sexual chemistry I wouldn’t limit myself because I use the label “gay”. (Really I’m about 90% along the spectrum to gay, but it’s easier just to say gay) For other friends they don’t have this, they are just “gay” and have zero interest in someone not the same sex and it’s not a choice that’s just how they are whether that’s through genes or environmental factors.

People have conscious control over how they act and who they sleep with but I’m almost certain they don’t have control over their sexuality.


As far as I understand it, "born this way" may as well be true.

Environmental factors have never been identified, and there is no clue as to when the determination is made. The sexual orientation can only really be observed/felt around puberty, but it seems to be determined long before.


> Environmental factors have never been identified, and there is no clue as to when the determination is made.

> but it seems to be determined long before [puberty].

If your first statement is true, your second statement has no basis. If your second statement is based on anything, your first statement is false.

Just pointing this out because I'm curious what the actual findings in this area are.


You don't need to know any deciding factors to observe the decision.

Sexual orientation, at least if we are talking about mostly-heterosexual vs mostly-homosexual as a trait is first observable around puberty, and doesn't seem to change, ever.

So puberty is an upper bound for the determination having been made. And I really can't imagine that it would be this hard to figure out what factors "turn someone gay" if the decision is made closer to puberty.

If it were already determined at birth, much like gender, it would fit with what we observe about homosexuality not being a choice, not being "curable" or "preventable".

I'm not a scientist with deep knowledge in this topic, but from what I understand, there is no evidence pointing to the determination happening after birth.


> So puberty is an upper bound for the determination having been made.

So there are in fact some "clues as to when the determination is made". Clues such as this one and others you pointed out.

This was really all I was confused about.


This is a bit like the question if people are born into poor families. As a kid you are never to blame for the circumstances and environment you have been born into.

You cannot choose to be born into a poor family, like you cannot choose beeing the youngest silbling, having a depression, being left handed or developing interest for the same sex.

Things like these happen to us independent of what we want, which is precisely the reason why it makes no sense to use atributes like these to single out individuals and spread falsehoods and hatered.

The weirdest thing is that everyone should know this, because we know that you can’t just decide with whom you fall in love with.

So just because there is no genetic deposition it doesn’t necessarily indicate that you can choose freely. Especially with desires that are rooted deep within, you can’t just go and decide that you have different desires from now on. That doesn’t mean these desires can’t change their shape over time, but influencing the how and what is neither easy nor possible in most cases.


I wouldn't go far to say that there is no genetic basis for sexuality. There is no single gene for aspergers, but we're pretty sure it's not a lifestyle choice.


It would be exceptional if sexual orientation was the one complex trait with no genetic component.


It's worth noting that "ambiguously somewhere between discovered and constructed, and often seen to change over time" does not at all imply "can change on a whim" or "can turn on a dime".


That there is no single genetic cause of same-sex sexual behavior is not at all the same as saying that 'born this way' is not true. Firstly, there may be multiple genes involved. Also, there is some evidence that the environment in the uterus plays a role. Also, that one study adds some evidence a certain way does not mean that we should forget everything that was found in the past. Including the fact that twins have a much higher chance to both be homosexual and the research of Simon LeVay.

I also am not sure we should draw much of a conclusion about what activists are saying. Activism seems to like aligning itself with what is most modern. That 'born this way' is now trending down says very little about either truth or what is going to happen in the future. Modern activism seems to be aligning itself with smaller and smaller minorities. Not that the people in said minorities don't also deserve to be treated fairly. People should take what people say about their sexual nature at face value instead of needing to know the precise label for something before being able to take it seriously. When we are talking about smaller and smaller minorities there will not be a label that is widely known for everyone.

To add some personal anecdata: my gay sexual nature seems to be about as fluid as rock.


Your comment is insightful but I feel like you're creating a false dichotomy:

>That's a far cry from the prevailing narrative from just 10 or 15 years ago, when very few gay people would admit that they might have any conscious control over being gay.

There's a large gap between "I'm gay because it's in my genes and I was born this way" and "I consciously chose to be gay". Social pressure and environment can probably play a role. Maybe (probably?) some gay people wouldn't have been gay if they had been raised in a different environment and vice-versa, but that doesn't mean that they ever consciously decided one way or the other the way you decide to go vegan or learn Japanese.

I like to think that sexuality is like food, music or anything else, what you like and don't like might be influenced by genes but it's obviously not the only factor at play. I doubt there's a gene for liking pineapple on pizza, yet here we are.


This is very anecdotal, and it's not what the research is saying. They also published a website which summarizes their findingshttps://geneticsexbehavior.info/what-we-found/

However we probably agree on two things: sexual orientation is not always a scale where the more you are attracted to one sex, the less you are attracted to another. And as many articles stated, the result for this study mostly means that we are not close to having a blood test that can determine if a person is gay.


> The "born this way" aspect of gay activism

Gays aren't the only ones who say they are born that way. As far as I know, everyone who is straight does too. Not that I researched it scientifically, but every straight person I know believes they were born straight, and that heterosexual animals were born heterosexual too.

How many people believe that heterosexuality is a choice?


The danger with “born this way” has always been that one day societies where there were social or political pressures and had the technology would try to “breed it out”. Maybe not in most western societies but possibly in less accepting societies.


Same sex couples cannot pass on their genes. That alone is a huge barrier for a "gay" gene to establish itself.


Neither men nor women need to have an ounce of interest in the other sex to reproduce...

There are lots of stories of homosexual men following societal pressure to create offspring.


Genetic vs fluid is a false dichotomy. Whether you are the way you are because of your genes or because of conditions in early development (perhaps as far back as the womb), either way you don't get to choose.


>Now, I'm seeing more and more LGB people freely admit what had been considered an open secret: that many of those who insisted that they were "born this way" actually consider sexual orientation not to be immutable, but fluid, to various degrees.

You're assuming that "being born gay" implies a static, albeit nonbinary, sexual orientation, and you seem to be confusing the concept of sexual orientation with gender identity.

Yes, it's possible to be genderfluid and to be attracted to both men and women, to different degrees at different times, but none of that implies a conscious choice to "be gay." Do you believe straight people choose to be straight? If not, why would it be the case that heterosexuality is genetically determined, but not homosexuality or bisexuality?


> you seem to be confusing the concept of sexual orientation with gender identity.

I don't think I am. There is gender fluidity and sexual fluidity, and I'm talking about the latter.

https://en.wikipedia.org/wiki/Sexual_fluidity


You clearly didn't read the article and misunderstood the title of the article. It says no single genetic cause. There are in fact, multiple genetic causes instead.


Moving on from the victim mentality has been a good thing for the gay community.


The "victim mentality" comes from being a victim, to imply otherwise is outrageous.


[flagged]


Some people claim to freely choose their sexuality. This article cites several examples:

http://www.bbc.com/future/story/20160627-i-am-gay-but-i-wasn...

Does this mean that every gay (or straight) person perceives their sexual attractions to be conscious decisions? No, but if you continue to insist that it's preposterous in the face of counterexamples, particularly counterexamples from gay people themselves, then I don't know how to respond to your outrage.

It's one thing to say, "Oh, I think such counterexamples are few and far between," but to say the very idea is preposterous just doesn't jibe with reality.


If someone has a desire for or the capability to enjoy sex with both males and females, they are neither heterosexual, nor homosexual. They also do not change their sexuality. They are simply bisexual. The fluidity here lies in whether someone has at some point in time more interest in women or men and which desire they act upon. If one's interest in one of the sexes goes to zero, then one could argue that persons sexuality did indeed change from bisexual to hetero- or homo-sexual.

Bisexuals indeed have the unique opportunity to "decide" which side of their sexuality they pursue, because they enjoy both. That's what makes them different from "true" heterosexuals and homosexuals who can not enjoy both. (Though one could argue a homosexual forcing himself to have sex with a woman and make a family is not truly homosexual and we do know that's possible and happened quite often. I will leave that to the philosophers.)

Please keep in mind I am not even arguing for the "born this way" view. I have a "It does not matter" stance. I welcome ideology free research to clear it up though, but don't we already know the results? Both genes and environment play a role...


Pointing out that some people can feels like a lame excuse for justifying doubt when someone says they can’t. Almost everyone does not choose their orientation.

It’s not a growing trend to suggest people can control this. It is perhaps a trend that people acknowledge things change over time. Those two are not the same.


[flagged]


The original commenters comment is nothing but jeer based on personal anecdotes. I could have commented with studies about gay conversion therapies and more arguments, but I am really not in the mood to argue with internet strangers. I still felt compelled to at least call out the venomous diction used here.


How else should outrage be communicated? I think deriding someone's sense of outrage is much less humanizing than caring about it. Caring about other's outrage is a basic ingredient in empathy.


[flagged]


If a family member or a friend seemed outraged at something would you tell them they were being childish? Or would you try to work out why they were outraged?


This is not really that surprising considering that the closer we look it seems like all genes affect complex traits, the omnigenic theory.

https://www.quantamagazine.org/omnigenic-model-suggests-that...


I have read a few cases of identical twins having different sexual orientation. Perhaps they are also good subjects of study, since their genetic make up are so similar, it would be easy to identify if/which genes correlates to sexual orientation.


Garbage in, garbage out. This study doesn't mean anything as it relies on information provided to 23 and me. The question asked if a person had a same sex experience, which doesn't mean a person is gay, bi or straight. Further there are plenty of people that wouldn't answer truthfully to the question for a multitude of reasons.

Good for advertising clicks and idiotic comments that have already started to appear.


> The question asked if a person had a same sex experience

Yeah i found that weird too. a Sexual experience is not "orientation"

Another interesting thing is that homosexual people use 23andme more frequently than the rest. Perhaps looking for clues like this


The theory of gay gene couldn't have been supported by the evolutionary algorithms.

Natural selection means that a trait like male homosexuality, if it had a genetic component, couldn't have persisted over evolutionary time if the individuals that carry the genes associated with that trait are not reproducing.

In my observation of two contrasting cultures that I grew up in, it could be better explained by sociology than genetics.


>The theory of gay gene couldn't have been supported by the evolutionary algorithms.

We have genetic diseases that kill people before they reach adulthood. We have gay people who get married, make kids, and feel zero sexual attraction to their spouse.

Evolution is a complex process. It's not a mere "more offspring = everyone else disappears" deal.


Yes it is totally supported by evolutionary algorithms. Traits that are harmful in some situations and beneficial in others can be passed on, like sickle cell anemia which gives a degree of protection against malaria. The same as traits which are beneficial to some of your offspring and advantageous to others, like a strong jaw. Which would probably look better on your sons than your daughter.

It can be evolutionary advantageous for some of your kids to come first, even if it means others come last, rather than all your kids coming second.


We have two conflicting pattern matching algorithms: Being attracted to females (smell, sound of voice, body composition) and being attracted to males.

A "male gay gene" could evolutionary surivive if it leads to boy crazy girls. Vice versa for a "lesbian gene".

In fact the study did find that partly different genetics were correlated for lesbians and for gays.


There has been societal pressure, extreme societal pressure for the last couple of thousand years, to get married and have kids which will pass along any gay genes. This would also make those applying this social pressure responsible for it's prevalence.


> Natural selection means that a trait like male homosexuality, if it had a genetic component, couldn't have persisted over evolutionary time if the individuals that carry the genes associated with that trait are not reproducing.

Not really, if we go back to time people were prosecuted for being homosexual. They used to have a wife and kid but still practised homosexuality in private or killed their desires and gave it up at great pain and sufferings.

It will take time for natrual selection to remove Homosexual genes (if we believe they exit) if they've full freedom and aren't forced to have kids.


Is prosecuting people for homosexuality genetic, or something that could perhaps change pretty rapidly? Perhaps for a million years, there were gay genes and gay people and no problem with it, then for five thousand years people had a problem with it. If humans have a gay gene, almost certainly there's some less social animals have a gay gene.


The key takeway is easily lost:

"genetics seemed to account for between 8 and 25 percent of the behavior. The rest was presumably a result of environmental or other biological influences. "

There is a lot of other research which identify these "other biological influences" as hormonal imbalance during the pregnacy, which in most severe cases causes a child to be transgender, in milder ones gay (this kind of explains "drag queens", gay man who identify as male, but still like to dress up as women sometimes. Not sure if there's a female counterpart to this phenomenon).


I get the sentiment but the title is misleading. There IS a significant genetic contribution, but it's polygenic.


That's why it says "no single genetic cause" and not "no genetic cause".


Technically true, and I'm sure the title wasn't intended to have that effect, but judging by the other comments, it appears some people still seem to be led to believe it meant "no genetic cause" - so it's still worth pointing out.

But yes, that's not necessarily malice or incompetence on the part of the title's author.


> But yes, that's not necessarily malice or incompetence on the part of the title's author.

If it's not malice, then it's linguistic incompetence.


Well, incompetence in that they didn't manage to achieve clarity for all readers, but not in the sense that someone else would've been able to think of a better title that would achieve that, I think.


Sure they would: "Study Finds No Unique Genetic Cause of Same-Sex Sexual Behavior".


It can kinda easily be misread as "not a single one".


I couldn't help reading single as an absolute zero and not a "potentially multiple"


Yet a handful of comments here are already jumping to the "it's environmental, not genetic" conclusion


It's also raging across the right wing internet. Has been for 3 days. Facts don't matter, even here.


Doesn't change the fact that it is misleading. "No single X cause" sounds as if it has no basis in X.


That’s “prone to misreading”, not “misleading”. The title is correct as written but there’s an argument for using a different wording such as “no simple” to reduce the chances of readers misreading it and jumping to conclusions.


Indeed, you're correct. I don't know if someone put it like this intentionally or not, but looking at the number of people who jumped into the incorrect conclusion, it has the same effect as misleading headline.


Something that’s prone to misreading is misleading. Intent doesn’t factor into whether something is misleading or not and neither does when something is in some sense correct but not understood correctly by many people.

Language can be used in too many ways and not all correct ways to use it are also easily understood. Often enough that doesn’t matter because of context but here context leads actually to people coming to the wrong conclusion because the well known conflict is between some (any) kind of genetic origin of homosexuality and environmental factors being responsible.


Right, and I don't think anyone would expect any complex behavior to be brought on by changes in only a few proteins.


You might be surprised how mane really complex outcomes can come from a single mutation.


I should clarify what I mean... yes, single mutations can definitely have far-reaching effects, but you would not expect a high-level emergent behavior to be the result of one or a few genes.


That single mutation could affect level of some hormone during som3 crucial step of brain development and that might result in some complex behavioral changes.


How did they discover that, given the curse of dimensionality? If the genetic contribution is significant, how do they know it's not some unreproducible model that is significant due to it having too many parameters (thousands of genes)?

Or do they have a theoretical model of homosexuality and took just the genes that the model predicts should point to it?


Inheritability of a trait can be inferred through statistic means, though I feel like there is too much confidence around such computations, given that it is virtually impossible to isolate environment from genetics in Humans.

But when looking for specific mutations, the sum of all these effects is often just a small fraction of that inheritability, suggesting that the interaction of the genes and the environment is more complex than can be captured with such models.


Maybe akin to the IQ story. Polygenic scores have been shown in at least 20 studies to predict IQ & educational attainment. "Childhood intelligence is heritable, highly polygenic and associated with FNBP1L"

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3935975/


statistics


Curse of dimensionality and statistical significance are terms I used in my comment. I'm quite aware of the statistical methods and am a bit confused about how they avoid the dimensionality problem.

I'm pretty sure I could get statistical significance for any trait with a highly dimensional dataset.


Rather than making armchair dismissals, consider looking at the paper and its citations which discuss the statistical methods used. From a cursory glance, it looks like they use a standard model of how genes affect traits, which uses O(N) parameters for N genes, so the "curse of dimensionality" would not apply.


When there's thousands of genes then it applies.


[citation needed]


It’s a scientific study so the citation is literally present in the story if you want to learn what they did:

http://dx.doi.org/10.1126/science.aat7693


This needs to be at top. Lots of commenters seem to have misunderstood the title just as this comment suggests.


A lot of otherwise smart people in here didn't read the article and are popping off about how gays choose to be gay.

The article says that it is a POLYGENIC situation, as in "not ONE gene, but many."


To make it simple to understand I think "same-sexual behavior" can be compared to left or right handedness. There is not a single gene that determines it (probably more than 40) but it is certainly not a thing people can choose or that can be easily changed during life. More about handedness https://ghr.nlm.nih.gov/primer/traits/handedness


As someone who knows nothing about this subject, if the cause doesn't appear to be genetic then what does that leave? Environmental? Something else?


The title doesn’t mean “the cause is not genetic”, but rather “the cause does not appear to be a single obvious gene”.

In reality there are going to be a bunch of different factors. Genetic predisposition is certainly likely to be one of them. Environmental factors too - like the hormonal environment in the womb, which I seem to remember had some correlation. Upbringing and social factors will also play an effect - a child with a strongly homophobic upbringing is less likely to explore their sexuality and end up identifying or embracing same-sex attraction.


Erm. You apparently don't know a lot about homosexuality... Homosexual children having problems with homophobic parents is a pretty common theme.

Also, same-sex attraction usually occurs long before any kind of "exploration", and doesn't seem to be any more controllable or malleable than heterosexuals would be able to control their attraction to the other sex.


> You apparently don't know a lot about homosexuality.

What in the parent comment makes you think this way (besides being an awful way to introduce an opinion)? He's just stating that someone with homophobic parents will probably be discouraged to explore, accept, or even recognize his sexual orientation. More broadly, that environmental factors will play a role.

And yes, I guess it's not more malleable than any other sexual orientation. It could happen to heterosexual children in an heterophobic society, too.


While I may not have intended my reply as being as insulting as it came across, I don't think I'm very wrong on that count.

I just get the feeling that you believe homosexuality to be something that can be consciously influenced by the individual himself or his social circle. And that can be a harmful attitude.

And the suggestion that "homosexuals would behave equally badly in a heterophobic society" is at best unhelpful.


I didn’t read that comment the same way you did: note the words around “identify” - I read that as fully cognizant of the history of persecution causing people to go by labels they knew weren’t correct but more socially acceptable.


We aren't talking about homosexual behavior but rather about homosexual attraction/orientation.

So if somebody hides his homosexual orientation, that's not what the study would refer to as heterosexual orientation.


I’m pretty confident I know a decent amount about homosexuality :)

At no point did I say that it was uncommon for homosexual children to have homophobic parents. That obviously happens all the time.

But I think you are trying to use overly precise ideas to analyse human sexuality. It’s complex and messy and the result of many different factors. You can’t completely isolate sexual attraction from identity or social background; indeed it seems blindingly obvious to me that upbringing would have an effect on an individual’s willingness to think about, accept or acknowledge any latent same-sex attraction they experience. It can be hard for an individual who is raised to reject same-sex sexual activity as perverted or morally wrong to even consider the possibility that it’s something they might experience themselves. People ignore or reject aspects of themselves all the time.

I can’t be certain, but my experience suggests that human sexuality is probably much more fluid than we generally expect as a result of long-standing social conventions. This is something that might change as same-sex relationships lose their taboo. And maybe I’m totally wrong; maybe homosexuality is just the result of a bunch of physiological changes. I find it hard to reconcile though.


I didn't want to offend you, so I have to apologize.

Many homosexuals really don't like the Idea of their sexual identity being "fluid". It doesn't seem to be the case that people "find out" they are homosexual later in life. They usually know it in puberty, even if they may not be able to clearly articulate it.

Talking about sexual identity as fluid is very close to saying it is a choice, curable or preventable, and that idea is causing a lot of harm.

Bisexual behavior or identity is something different again. And it's not clear to me if these are homo/heterosexuals also being able to "function" in the other way, or if it is a third kind of sexual orientation. From what I know it seems to be that a lot more heterosexuals are able to feel homosexual attraction/arousal than we may think. And homosexuals, especially in the past, have led opposite-sex relationships with all the "trappings".


Some of the most important things to know about homosexuality is that it's neither a choice, curable nor preventable.

There indeed seems to be an immutable difference between those who are primarily/exclusively attracted to the same or the opposite sex. But actual behavior, affected by culture and circumstances, does make all of this more difficult.

Homosexuals are often perfectly able to "function" in heterosexual intercourse, and heterosexuals in homosexual intercourse. But the study didn't ask for that, they asked for the underlying preference. They may even have used physical measurements. Yes, there are studies where the participants are exposed to different stimuli and their arousal is measured physiologically.


It is genetic in a number people but environmental factors play a big part. More than one thing can cause it.

One reason: Later children in large families are more likely to be gay but the reason might be related to the mother already being exposed to hormones with earlier children. On an evolutionary scale this might make sense that the first born are more likely not to be gay as to pass on the genes but later children population control might make more sense.

Another might be hormone levels of the mother.

Another might be gene related where physical changes are different

Another might be gene related that increase gender fluidity which combined with society can shape sexuality

But we do know there isn't a single simple gene.


It can be compared to a dice. If you throw a dice, the outcome is determined by physical laws. But you still can't predict it, because the problem is too complex.

Sexual orientation seems to be somewhat similar, in that environmental factors, akin to chance, lead to choosing one path among several.


What do you think causes big noses?


I would like to say your comment is right on the nose, but it really isn't a helpful question at all.


both?


There’s plenty of evidence to suggest some portion of likelihood of being gay is controlled by parental hormones. E.g. the probability of being gay is observably higher in men born after an older brother.

So... this was obviously going to be true.


If I understand correctly, this result is exactly equivalent to "no single genetic cause for heterosexual behavior", which does not seem as dramatic.


What about genetic causes in the parent(s)? Such as a genetic cause in the mother affecting the hormonal levels in uterus.


That should still result in specific mutations having significant effects.

And maternal effects are a thing that can be computed statistically, both as a genetic and environmental factor.

And it's not helpful to confuse sexual orientation with hormonal causes or effects.


I wonder what if it's a learned behaviour.

I used to very odd kid and mostly spent my life around girls from very early age.

I almost never had male friends which ofc changed in late teenage.

Now, don't find females that attractive and mostly spend time with guys.

Don't call me sexist or smth but I find it's more fun to work with guys. That's my preference.


Proximity can go both ways... You might as well develop a strong liking of girls/women because of proximity.

I've been bombarded from young age (by pop culture, TV, magazines, porn) by thin women wearing make-up. I have a strong sexual preference for thin (fitspo thin, not anorexic thin) women and a strong dislike of women wearing make-up. Go figure...


There is a difference between the neuro-biological sexual orientation and actual sexual behavior.

Sexual behavior is definitely learned. But despite centuries of "theories" or convictions about "what experiences turn people gay", nothing has been identified scientifically.


> Don't call me sexist

Why it would be sexist? It's your personal preference and nobody's else but yours.


I always thought the claim of a genetic cause for sexuality was a bit premature. Even if one is “born this way”, that doesn’t necessarily mean it’s genetic.


I find it difficult to believe a universal genetic cause since same-sex relationships generally don’t produce off-spring and would be naturally selected out.


In fact I read some time ago that one mutation that does have a small contribution to sexual orientation, has the same allele frequency in most Human populations, suggesting that even the "gay" allele is positively selected for.

A Human individual's fitness affects the chances of his whole family. And it's just not true that Homosexuals don't have children. In practice they have fewer children, but more than you might think.


This is like saying there could be no genetic cause of blindness as blindness is naturally selected against.




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