Is homosexuality genetic?

[Denise]

Yes, phobos, I agree. That's why I was asking if that was also true in animal populations. Meaning that there would be an evolutionary advantage to homosexuality if the animals do not produce offspring.That is, if the population is getting to the point of not being able to be sustained by the habitat. But, alas, everyone is focusing on Titanpoint. Yet, I sit here in the chair with my hand up like Horseshack "OOh! OOh! OOh!"

 

[phobos]

Yes, phobos, I agree. That's why I was asking if that was also true in animal populations. Meaning that there would be an evolutionary advantage to homosexuality if the animals do not produce offspring.That is, if the population is getting to the point of not being able to be sustained by the habitat. But, alas, everyone is focusing on Titanpoint. Yet, I sit here in the chair with my hand up like Horseshack "OOh! OOh! OOh!"

Ah! Quite possible, then. I could, in a saturated population, decide not to breed, and still benefit my genes by helping my relatives with the work of rearing their children. Genetically, every brother is as valuable to me as one of my own children, since they carry 50% of my DNA. A nephew is worth 25%, and a cousin 12.5%. Such a strategy would become worthwhile in a population crisis, where it makes sense to emphasise quality over quantity in the business of breeding.

It seems plausible that homosexuality might be the method used to switch an organism from breeder to supporter. Asexuality would be optimal, though, and this is the solution worker bees have arrived at. Maybe sex is too fundamental in the mammal, and so the quick-hack of homosexuality was good enough for evolutionary purposes?

This would also mean that homosexuality is a genetic contingency plan, and we shouldn't expect a clear-cut 'gay gene'. Any gene or genes for homosexuality would, under this model, only become activated as a result of environmental factors.

IANABiologist, however, and so I might well be talking out of my gaping goatse.

 

[Denise]

Well, going way out there here....

What if the percentage of homosexual animals rises with maternal malnourishment? So, there is a population of animals that are competing for scarce resources, and, as a result, many of the animals are malnourished. It would be better for the population as a whole, because none of them are fully nourshed, to have less of a population next generation so that they fit into their habitat. It seems to me that animal homosexual has been noted in the wild because they do not reproduce. They don't have the peer pressure that humans have to be heterosexual. So, as a result of the malnourishment, the next generation has a higher percentage of homosexuals that will not reproduce. Yes, I know it's out there.

 

[phobos]

Well, going way out there here....

What if the percentage of homosexual animals rises with maternal malnourishment? So, there is a population of animals that are competing for scarce resources, and, as a result, many of the animals are malnourished. It would be better for the population as a whole, because none of them are fully nourshed, to have less of a population next generation so that they fit into their habitat. It seems to me that animal homosexual has been noted in the wild because they do not reproduce. They don't have the peer pressure that humans have to be heterosexual. So, as a result of the malnourishment, the next generation has a higher percentage of homosexuals that will not reproduce. Yes, I know it's out there.

Let's take this line of thought further. What if things look REALLY bad? Suppose I've been born in a litter. Suppose food is dangerously short, and suppose that I happen to be the weakest of my siblings, the runt of the litter, the least likely to be a breeding success. What's my best strategy to preserve my genes?

Suicide.

If I die on the spot, then my brothers and sisters will have more food. If they have more food, then they'll have more success in propagating their genes, many of which are my genes which they share. Some of those genes will say 'if you're the runt of the litter and food is very short, drop dead.'

Is this sort of thing observed in the wild? Runts and sickly young just dropping dead for no particular reason?

ISTR there was something like this in Selfish Gene, but I can't remember exactly what. I shall look it up.

 

[Denise]

It has been observed that animals will decide not to feed one of their offsprings. So I don't think suicide really enters into the picture.

 

[phobos]

It has been observed that animals will decide not to feed one of their offsprings. So I don't think suicide really enters into the picture.

Wow. That's even more brutal. I had the mental image of noble self-sacrifice, whereas the reality is one where the parents genes say 'It's not worth your time and effort to feed that loser; let it die.' Selfish genes can be real _bastards_...

 

[DrChinese]

I'm curious about where this (1994) research ended up:

quote:
--------------------------------------------------------------------------------
WASHINGTON (AP) -- Two Canadian researchers have found
a link between the number of ridges in fingerprints and male
homosexuality, adding to the theory that sexual orientation is
determined before birth.

Hall JAY, Kimura D.
Dermatoglyphic asymmetry and sexual orientation in men.
Behavioral Neuroscience 1994;
108(6):1203-1206.
--------------------------------------------------------------------------------

I consider it self-evident that the number of ridges in a person's fingertips does not determine their sexual preferences. Does anyone reading this disagree?

What may not be so clear is that even finding a statistical corelation would still not demonstrate the biological nature of homosexuality.

Many studies detect spurious relationships. Such studies have no scientific value. It is not true - as stated in the quote - that this study would add to the theory that homosexuality is determined before birth. Unless of course the study identified an independent variable which was properly studied with random samples of the population, causal mechanisms hypothesized, etc.

This is an example of what I consider bad science. A spurious relationship is reported because it is interesting or controversial, when in reality there is no scientific value. Believe it or not, there are literally an infinite number of spurious corelations available to be studied. Don't be taken in.

 

[Dymanic]

This is an example of what I consider bad science. A spurious relationship is reported because it is interesting or controversial, when in reality there is no scientific value.

Thanks, Doc! (may I call you 'Doc'?)

That's more confirmation for what I had heard about those guys--that some of their work is considered... less than rigorous. I figure a skeptic's forum is a good place to air stuff like that out.

I consider it self-evident that the number of ridges in a person's fingertips does not determine their sexual preferences. Does anyone reading this disagree?

I would have assumed they were not suggesting that the ridges determine sexual orientation, but simply that the increased numbers in ridges occur more frequently among homosexual men (for whatever reason--I doubt they claimed to know that).

What may not be so clear is that even finding a statistical corelation would still not demonstrate the biological nature of homosexuality.

You're right--that isn't so clear to me. Can you expand on that? How else could we confirm a thing like that, if not on a statistical corelation of some type? I obviously haven't read their book, and I'm guessing you haven't either--but suppose they did identify an independent variable, etc.?

 

[garys_2k]

Don't forget that a definition of homosexuality is also hard to nail down. One incident, a few, thoughts about it, maybe 10% of sexual experiences with a same-sex partner? What and who decides the lines between hetero, bi and homosexuality?

I suspect that these vague definitions will cause comparing studies or surveys to be very difficult.

 

[JamesM]

How else could we confirm a thing like that, if not on a statistical corelation of some type?

Probably not a useful answer to your question, but two things to look out for in statistical studies:

1. Were the subjects assigned randomly to the different groups? You can easily do this, for example, when testing for the efficacy of drugs. One group gets the drug, the other gets a placebo. If you do this, and get a statistically significant result, you may reasonably state cause and effect, e.g. taking the drug makes you better. It can be argued that bad luck meant that healthier people were put in the drug-taking group, but that can be accounted for by tests of significance.

In a study of something like homosexuality, however, you can't assign people to the homosexual and non-homosexual groups. Even if you had some special ray-gun which turned people gay, you would probably run foul of ethics committees before getting your hands on the cash to carry out the experiment. Here, you can only do a retrospective study, and you can never be sure that there isn't some hidden variable at work that you've not identified. At best you can only say the correlation is suggestive, but you can't say what's a cause and what's an effect (maybe fingertip ridges can turn you gay?) - you may have two effects.

Of course, problems with causation vs correlation can also apply to randomised studies. If you have a plausible mechanism to take you from cause to effect, you're on much safer ground.

2. Were the test subjects selected randomly from the general population, or from some subset? If they weren't from the general population (which, let's face it, is extremely difficult to arrange), then strictly speaking,it's only valid to apply your conclusions to the population from which you sampled. However, in many cases, the results would be extremely suggestive in applying to the population as a whole.

 

[DrChinese]

Thanks, Doc! (may I call you 'Doc'?)

I would have assumed they were not suggesting that the ridges determine sexual orientation, but simply that the increased numbers in ridges occur more frequently among homosexual men (for whatever reason--I doubt they claimed to know that).

I obviously haven't read their book, and I'm guessing you haven't either--but suppose they did identify an independent variable, etc.?

Call me Doc, sure (LOL).

The deal about the number of ridges is the spurious correlation. The existence of the spurious correlation is meaningless. For instance, is it "more" or "less" ridges we are expecting in gays? Neither, you say, it is just that if there is a relationship it proves the genetic basis of homosexuality. Not true.

This is the fallacy of the spurious correlation. It leads us to believe that even if we don't know what the "true" independent variable is, it must exist. But such is not the case. It is a trick, and you have to alert to catch it. Scientists make this mistake all the time.

Let me use a spurious correlation to prove that homosexuality is NOT based on genetics. If homosexuality is not genetic, then presumably it is learned. If I prove it is learned, then by the logic of the correlation with fingerprint ridges, it must not be genetic.

Suppose I prove that gays listen to Barbra Streisand's music. This correlation (made up, but plausible if you saw that Kevin Kline movie) would say that gays learn to like such music, just as they learn to be gay. This would be a spurious correlation - no scientific value.

 

[Darat]

There is a interesting news piece in New Scientist

http://www.newscientist.com/news/news.jsp?id=ns99993008

A study of gay sheep appears to confirm the controversial suggestion that there is a biological basis for sexual preference.
The work shows that rams that prefer male sexual partners had small but distinct differences in a part of the brain called the hypothalamus, when compared with rams that preferred to mate with ewes.

...

 

[INRM]

I have a theory, but it's that there are multiple factors which determine homosexuality.

I've seen many types of gays but these are the two most common.

The first type is the one you rarely see on TV. They're the ordinary looking gay guy, with no speech impediment (lisp) whatsoever. They look ordinary, and act normally.

The second type are the kind who are flaming gays. They act all feminine and have a lisp, and walk with their wrists limped. Rather than saying "Oh God" like an ordinary person would, they would say "ooh, goodneth!" while limping their wrist.

The second type is the most popular view of gays.

Now, some gays have gender-recognition issues too! The kinds who either act like women, or those who have sex-change operations (I've talked to one).

The second one have no gender recognition disorders; they know they're men, they're happy being men; they just like other men.

Now, it gets even more complicated because some straight men have gender-recognition disorders. A film on HBO called "Normal" was based upon this.

And there *are* men who like women who have undergone sex-change operations.


Some gays knew they were gay from childhood. And others discovered they were gay in their teens, either after their first sexual encounter, or after a few times when they just realized they didn't like it. That must suck.

That's another interesting issue.

I think there are varying degrees of homosexuality, just as if there are varying degrees of skin-color. I'm a bit tan myself. I'm not blank white, or pure-black, I'm right in the middle.

IIRC, there are seven different alleles for producing skin color...

I think there are multi-alleles for determining homosexuality.

Some of these alleles may ALSO play a role in gender recognition, as some gays ALSO act effeminate. A much higher-percentage than in straight men.

It's definetly a recessive trait.

There is a final factor: environmental-- I believe that in some cases the homosexuality trait surfacing outright is probabilistic... just as some people have fairly light-skin, but can get real-tan when the time arises.

I believe that the trait may not surface if the right "triggers" aren't set off. Could be temperature like in the fruit-flies, or it could be something different in human beings... It could be excessive stress, it could be being raised around people of an opposite gender.

There are some guys, even if they were raised as guys, would turn out straight no matter what. There are guys where if they were raised around girls they would turn gay... others would turn gay even if they were raised around men.

But whatever this trigger, or triggers are, we don't know what they are. When they are set off, however, homosexuality surfaces.

Some cases it might not be a slight homosexuality (like a slight-tan), it could be much more. Such that the person could be homosexual no matter what. And in some cases (extreme), the person can realize they are gay from the start.

Despite this, the gender recognition factor... not all gays have it. Some can be quite openly gay and not have any trouble figuring out what gender they are. Some do think they were born in the wrong body. Like a man in a woman's body. Or the other way around.

For the most part, this I should mention. All the people that knew they were gay from the start... they were probably all women. One might have been a guy, but that's it.

-INRM
P.S. If some of this stuff doesn't make any sense, it's because I'm really tired.

 

[DrChinese]

There is a interesting news piece in New Scientist

http://www.newscientist.com/news/news.jsp?id=ns99993008

See above about spurious correlations. Unless there is a causal mechanism between the size of the hypothalamus and sexuality, it is a spurious relationship and has no scientific value.

I don't care what magazine reprints a study, it is evidence of exactly nothing. This problem is more common than you think. What is the hypothesized causal mechanism? Where is the independent variable? If you don't know what they are, how can you measure it? That is the criticism of these types of studies.

It is a joke really. It used to be that the standard for such studies was that you came up with a hypothesis with a causal mechanism - an independent variable - and then prepared a rigorous study to support or deny the hypothesis. Nowadays, that is too difficult for most scientists. So they measure a relationship between two things with no known cause and effect relationship - because it is easy. Then they say... hmmm, maybe there is a cause-effect relationship in there somewhere, let's do another study!

But guess what - no matter how many times the study is done, and no matter what the results, it will NEVER prove the hypothesis. Not if it is a spurious relationship, which can't be determined by the study itself.

 

[BillyJoe]

If anyone in this thread is _actually_ gay... comments?

.

 

[Phaycops]

Don't forget that a definition of homosexuality is also hard to nail down. One incident, a few, thoughts about it, maybe 10% of sexual experiences with a same-sex partner? What and who decides the lines between hetero, bi and homosexuality?

I suspect that these vague definitions will cause comparing studies or surveys to be very difficult.

This is what I want to know. Obviously, in fruit flies, it is obvious. But fruit flies don't have human emotions and needs, and certainly aren't exposed to human media

Consider the tendency of college-freshman-aged women to identify as "bisexual," fool around with some girls, and then go get married (to a guy) and have kids after graduation, never to look back. It has been hypothesized by lesbians I have known that one reason for this is that there's this human desire to be a part of a group, but is also reinforced by cultural messages saying that it's ok for girls to sleep together (it's just gross if it's guys ). How coudl you possibly assign these girls to "hetero" or "homo" groups? If they were just "doin it to be cool," wouldn't this skew your study in some way?

And anyway, doesn't it seem more likely that in reality it's a combination of factors and not just one gene? But then, people don't like to hear that kind of thing. It's too difficult and doesn't sell newspapers

 

[arcticpenguin]

Consider the tendency of college-freshman-aged women to identify as "bisexual," fool around with some girls, and then go get married (to a guy) and have kids after graduation, never to look back.

I have heard that at women-only colleges there is an acronym for this: LUG, lesbian until graduation.

 

[K-W]

Just speculation on my part, but I think if/when we do get an answer to this question it will be that its a very complicated genetic/enviromental interaction, and that there are multiple causes of the behaviors we lump together has homosexual. I think that the behavior of Homosexuality could be brought out by genetics, by cultural practices, or by a particular enviromental history. If this is the case than finding any patterns in the behavior would be extremely difficult. It would explain exprimentation, and the many variations in sexual preference and behavior.

 

[DrChinese]

Just speculation on my part, but I think if/when we do get an answer to this question it will be that its a very complicated genetic/enviromental interaction, and that there are multiple causes of the behaviors we lump together has homosexual. I think that the behavior of Homosexuality could be brought out by genetics, by cultural practices, or by a particular enviromental history. If this is the case than finding any patterns in the behavior would be extremely difficult. It would explain exprimentation, and the many variations in sexual preference and behavior.

Well said, I agree totally. Most analysis is oriented to demonstrating environment over genetics, or vice versa. Such a simplistic reduction of the mechanisms probably doesn't work for human behavior. It is the interactions of both one's environment and heredity which are fundamental to explaining what is observed.

 

[Phaycops]

Well said, I agree totally. Most analysis is oriented to demonstrating environment over genetics, or vice versa. Such a simplistic reduction of the mechanisms probably doesn't work for human behavior. It is the interactions of both one's environment and heredity which are fundamental to explaining what is observed.

I completely agree. But it doesn't change the fact that people want easy explanations for things. They want to be able to say "Oh, hey, I'm gay but it's genetic so you can't deny me basic rights anymore," or whatever. The whole debate is tinged with politics and agendas, you know, just like global warming, etc. People with agendas don't like messy things like, oh, I dunno, reality, because it's difficult.