Wouldn't a "gay gene" have to be matrilineal? (mission)

[Flappycat]

Rather, it might be more appropriate to say that it would be more likely to be matrilineal if there is some genetic origin.

Take siblings Xg and Yg of Mg. mDNA would only be carried by X, so the transmission of mDNA affecting Y would never be carried by Y in the first place, making the chances of Y reproducing almost irrelevant to the transmission of g because mitochondrial DNA wouldn't be affected much by the reproductive success of Y. If Xg and Xn (X normal) had equal odds of reproduction, little wonder that g was never entirely eliminated. g would only have been problematical on such occassions that an entire population had such a high Xg population that it wasn't producing a sufficient number of Yn to provide Xn and Xg with the y-chromosomes needed for reproduction.

Does this make sense? Can anyone find a flaw in my reasoning here?

[michel]

Originally Posted by Flappycat

Rather, it might be more appropriate to say that it would be more likely to be matrilineal if there is some genetic origin.

Take siblings Xg and Yg of Mg. mDNA would only be carried by X, so the transmission of mDNA affecting Y would never be carried by Y in the first place, making the chances of Y reproducing almost irrelevant to the transmission of g because mitochondrial DNA wouldn't be affected much by the reproductive success of Y. If Xg and Xn (X normal) had equal odds of reproduction, little wonder that g was never entirely eliminated. g would only have been problematical on such occassions that an entire population had such a high Xg population that it wasn't producing a sufficient number of Yn to provide Xn and Xg with the y-chromosomes needed for reproduction.

Does this make sense? Can anyone find a flaw in my reasoning here?

I might be able to if I could understand what you are saying........

[Flappycat]

Originally Posted by michel

I might be able to if I could understand what you are saying........

Basically, all I'm saying is that genes that are only affected by the reproductive success of female offspring would only require female offspring to have reproductive success for the genes to be passed to the next generation. Even if there were a gene transmitted through females that caused them to produce male offspring that are incapable of reproducing, the gene for it wouldn't be affected fatally by the reproductive success of male offspring. It would only depend upon female offspring to be transmitted from generation to generation BECAUSE males don't carry the gene in the first place.

[Nehustan]

It could be recessive, needing both X and Y in the parents to be recessive for that gene locus/locii, for the 'trait' to express, rather than solely dominant in the X. Personally I don't believe its genetic...but thats my slant.

[michel]

Originally Posted by Flappycat

Basically, all I'm saying is that genes that are only affected by the reproductive success of female offspring would only require female offspring to have reproductive success for the genes to be passed to the next generation. Even if there were a gene transmitted through females that caused them to produce male offspring that are incapable of reproducing, the gene for it wouldn't be affected fatally by the reproductive success of male offspring. It would only depend upon female offspring to be transmitted from generation to generation BECAUSE males don't carry the gene in the first place.

Sorry, I was messing around; I understood what you were saying, but haven't got a clue about genetics, nor biology.

[standing_on_one_foot]

Why precisely would a "gay gene" have to be on the X or Y chromosomes, do you know?

[Nehustan]

Is that a question to me SoOF?

[Endless]

There have been many studies, but none have concluded that there is such a thing as a gay gene. Recently it has been said that we are all gay to some extent - ie. It's a state of mind so to speak. Different things can sway it one way or another. You often hear of people getting married and having children and then 'finding out' they were gay - their state of mind has swung during this period. So it can swing back again if you are gay as well. It's a state of mind so to speak.
Perhaps genetically some people are more suspectible (if that's the right word) than others - i dunno, the mind is way way too complex. All i know is that it isn't fixed.

[Flappycat]

Endless, this is a hypothetical discussion about how a "gay gene," if there is such a thing, would be transmitted. This is not a discussion about your church's ex-gay group, the sanctity of marriage, what your particular misinterpretation of the Scriptures have to say about homosexuality, civil rights, "special rights," affirmative action, transexuality, morality, alternative energies, or how the Gay Agenda has an orbitting mind ray that someone's half-brother's father's fifth cousin, twice removed, saw in a heavenly vision, okay? This is purely a discussion about how a purely hypothetical "gay gene" could survive down the ages.

[Halcyon]

Originally Posted by Flappycat

Rather, it might be more appropriate to say that it would be more likely to be matrilineal if there is some genetic origin.

Take siblings Xg and Yg of Mg. mDNA would only be carried by X, so the transmission of mDNA affecting Y would never be carried by Y in the first place, making the chances of Y reproducing almost irrelevant to the transmission of g because mitochondrial DNA wouldn't be affected much by the reproductive success of Y. If Xg and Xn (X normal) had equal odds of reproduction, little wonder that g was never entirely eliminated. g would only have been problematical on such occassions that an entire population had such a high Xg population that it wasn't producing a sufficient number of Yn to provide Xn and Xg with the y-chromosomes needed for reproduction.

Does this make sense? Can anyone find a flaw in my reasoning here?

Erm... sorry flappycat, i studies genetics for three years and i'm having trouble trying to work out this paragraph, i'd be surprised if a non-biologist would get it.

First can you clarify some of your abbreviations for me;

I assume g = the gay gene? And that Xg is a gay female and Yg is a gay male? Xn and Yn being heterosexual? What the heck is Mg??? A homosexual mother?

By mDNA you are referring to mitochondiral DNA, that being the remainder of the mitochondria's own DNA that has not been relocated to the eukaryote nucleus. What has this small amount of DNA largely involved in ATP synthesis got to do with your supposed gay gene? The gay gene would not be in the mDNA since mitochondria have no sexes.

I'm a bit confused by some other stuff too. Both Xg and Yg would have the mother's mitochondria, Yg wouldn't be able to pass it on - but what has that got to do with anything?

Moving away from the seemingly dead end mDNA path.
Are you suggesting that the gay gene would be on the female's X chromosomes? If this was the case then, if it were only on one of her chromosomes any children she had, male or female, would have a 50:50 chance of being gay. They in turn would both have a 50:50 chance of passing the gene on to their offspring, the Yg male would not be prohibited from passing on his X, since gay men are not infertile.
Although a gay man in this scenario would always produce gay daughters, assuming that the gay gene is dominant. This isn't the case.

Or are you proposing that gay females would need/have a gay gene on both their X chromosomes?

Why are you assuming that such a gene would be on the sex chromosomes anyway? Its far more likely that since homosexuality is not linked to specific genders or even families, that such a gene would be on one of the other autosomal chromosomes.

Leaving the gay gene theory aside. It has been shown that sexual preference is determined in animals by hormone concentrations at specific points during fetal development.
For example, a female mouse embryo developing between two male mouse embryos will show greater expression of masculine behaviour (including attempting to mate with other females) than one of her sisters who developed next to only one male or between two female embryos.

Brain scans of sheep show differences in size of specific areas in heterosexual rams and ewes, in homosexual rams this area appears as in the females.

A 'gay gene' seems unlikely to me.