Gay sheep, forbidden science?

Science told: hands off gay sheep:

Scientists are conducting experiments to change the sexuality of "gay" sheep in a programme that critics fear could pave the way for breeding out homosexuality in humans.

You can read the whole article yourself. Randall Parker has been saying for years that genetic engineering will accentuate human differences as parents will choose to invest in alternative enhancements with their finite dollars. The vectors may remain the same, but the magnitudes could increase, as religious parents breed super-religious offspring, secular parents start spawning born atheists, and what not. There is a pretty obvious and straightforward way for homosexuals to calm down their fears that straight parents will genetically engineer out their orientation (ergo, community): breed gay babies. If scientists can understand homosexuality well enough to "cure" it, then they could certainly turn fetuses gay.

Update: Just to be clear, just because obligate homosexuality is likely of biological origin does not necessarily mean that it is genetically specified. The evolutionary reasoning is pretty simple, obligate homosexuality is a reproductive fitness killer. There is a hypothesis that "gay uncles" may enhance the fitness of their siblings, but while the coefficient of relatedness between a parent and child is 1/2, that between uncle and niece or nephew is 1/4.1 In other words the increase in fitness to the siblings has to be enormous in an inclusive fitness context. Another model for the biological origin of homosexuality is something like Toxoplasma gondii, a pathogenic infection which has a behavorial impact. Susceptibility to this putative pathogen might be genetically correlated, in other words some families might be more likely to be infected and exhibit "symptoms" than others. This story is less about genetics really than possible physiological re-wiring, which might have some psychological consequences.

This also highlights the fact that lot of the "re-working" of our species biological substrate might not have a big germline impact. I alluded to this when discussing the low fitness (sterility for males) of Down Syndrome individuals. But be able to re-work psychology and physiology "on the fly" based on personal and social preference will obviously have a big impact if it becomes common.

1 - There is an idea that homosexuality is a byproduct of another genetically controlled trait which has been under selection. In other words homosexuality is a correlated response in a population due to pleiotropy at a locus. But this falls under the same problem that the inclusive fitess hypothesis does: selection would operate against a locus which resulted in a predisposition toward non-reproductive behavior as the primary sexual outlet. If it is pleiotropy than it is likely a recent genetically controlled trait since it seems likely that modifier genes would have masked fitness reducing byproducts in short order. I also think that it if is pleiotropy that Quantitative Trait Loci studies would have picked it up by now because it has to be a gene of massive selective power and ergo large effect.

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With six billion people on the planet, most of whom will never be able to afford genetic screening of foetuses, such techniques are highly unlikely to affect the gene pool in any measurable way. Especially since affluent people tend to have few kids.

Do we even know for a fact that theism and sexuality are genetically determined or is it just a bunch of hearsay and conjecture?

Do we even know for a fact that theism and sexuality are genetically determined or is it just a bunch of hearsay and conjecture?

heritability for religious zeal is 0.5. concordance for homosexuality is 0.25.

homosexuality might not be 'genetic.' it might be an infection, no gene therapy needed. but in any case, obligate homosexuals are not more than 2% of the population, so this an issue of relevance mainly to homosexuls since that % could drop a fair amount. in any case, though it doesn't apply here lack of money isn't an issue, see sex selection.

PETA's big lie:

Just so you know. The false suggestion that the research is aimed at curing homosexuality was made by PETA. Yes, the animal rights group.

Of course PETA has their own motives for receiving press on this story. In fact, PETA heavily edited quotes by the researchers and even fabricated information to generate press coverage. Many weeks ago, a writer in the states looked into PETA false claims. Here's what he found:

http://thenexthurrah.typepad.com/the_next_hurrah/2006/09/peta_crosses_t…

We have an important clue about homosexuality with relevance to this discussion: the little-brother effect. Boys who have older brothers (but not girls, and not boys with older sisters) are more likely to be gay. This fits the criterion for a biological, but not genetic, determinant of sexuality and gives us a solid hypothesis to test (or rather, a parent hypothesis from which we can spin a lot of testable hypotheses): male but not female sexual orientations are "set" by the mother in utero.

Let's say that scientists discover a method for ensuring that all fetuses turn out to be heterosexuals.

So what?

By Caledonian (not verified) on 02 Jan 2007 #permalink

'Boys who have older brothers (but not girls, and not boys with older sisters) are more likely to be gay. This fits the criterion for a biological, but not genetic, determinant of sexuality and gives us a solid hypothesis to test (or rather, a parent hypothesis from which we can spin a lot of testable hypotheses): male but not female sexual orientations are "set" by the mother in utero.'

You would of course also have to evaluate the possibile effects of things like younger brothers being bullied or molested by older brothers, and differences in the way younger brothers are treated by parents.

You would of course also have to evaluate the possibile effects of things like younger brothers being bullied or molested by older brothers, and differences in the way younger brothers are treated by parents.

Already done. Adoption study (PDF):

Only biological older brothers, and not any other sibling characteristic, including nonbiological older brothers, predicted men's sexual orientation, regardless of the amount of time reared with these siblings.

By Jason Malloy (not verified) on 02 Jan 2007 #permalink

This is interesting to me since I spend a lot of time with animals, especially goats and sheep. It seems to me that animals don't really have an "orientation". I do think they associate sex behaviors with affection as well as other social behaviors like dominance. When a doe is in heat she is more likely to mount her friends then a doe she doesn't like. From my barnyard perspective, all healthy male animals (well, goats and sheep) have sex with other males as a normal part of their relationships. These "gay" behaviors don't get in the way of them reproducing at all. Whenever a buck (goat) in uniterested in the does he has a medical issue (sick, retained testicals or something like that) or has a hormonal problem. If he has sex with the boys then he'll have sex with the girls, it's just sex to him I think. As for sheep, the boys tend to fight rather than have sex with each other so people don't usually keep rams together. Animals just don't have the social crap to deal with that we do and they just don't draw the same lines we do. Having known a few sheep, I have to wonder how they defined "gay" in the sheep for this study. I hate to make assumptions but I suspect this study is totally meaningless because sheep have a very different social structure than we do.