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"Can we assume that homosexual tendencies are to some degree heritable"

25%. detected genes associated with homosexual sex are correlated with more sex partners in straight people

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What do we know about the 75%?

Also what's the pattern for the 25%? E.g is it that some gene common in gay men is evolutionary helpful only when it turns up straight women?

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founding

Re: "Will we see a neo-eugenics movement, to try to weed certain traits out of the population?"

We probably will see a social pattern of various individuals using new biotech (e.g., gene-editing?) to try and design their offspring for health, prowess, charisma, or other advantageous traits. Not a neo-eugenics *movement* to achieve a collective social outcome, but an emergent social phenomenon -- an expression of private, subjective optimization by parents, motivated by (a) altruism towards offspring and/or (b) status anxiety and vicarious ambition through lineage. Perhaps there will be two cultures?: a designer-baby culture, and a laissez-faire reproduction culture.

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The designer-baby culture will be very diverse, since different parents will have different--even radically different--ideas about what characteristics are desirable in their offspring.

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No. This is about preventing diversity. Desirable characteristics are standard and in a discreet range… tall, blond, blue eyed, good looking, athletic, high intelligence, disease free… goodness the Aryan master-race. I doubt short, fat, ugly, stupid will be much selected.

But it is likely that genetically ordered people will marry other genetically ordered people by arrangement and they will have genetically designed children, nothing left to chance/diversity.

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Back several decades, there were a raft of science fiction stories about what people would do when they could change their bodies. Mostly, they didn't turn themselves blond, blue-eyed, etc. (At least, they didn't after a while, after they got tired of all the blond, blue-eyed, etc.) They went for different: lizard skin, stuff like that. Makes me think a little of tattoos. The first ones were relatively small and unobtrusive, and often were covered up by business casual clothes. But they are getting bigger and more involved, and less able to be covered up.

Designer babies may be more interesting, and uglier and stupider, than you expect.

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These gifts may finally be available to all instead of a select lucky few who had the right ancestors.

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In the last few years it's become possible to do polygenic screening on embryos, you can do it now at your local clinic if you're doing IVF. This offers the opportunity for ~70% reduction of the possibility of many common disease traits like Type 1 Diabetes.

Since its merely picking amongst embryos already generated through IVF its fairly non-radical technology wise. Demand is robust.

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founding

In terms of moral psychology, embryo selection sidesteps controversy around gene-editing.

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Selective breeding to propagate desired characteristics inevitably inbreed undesirable characteristics as natural selection is thwarted. See dogs.

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founding

If private attempts to produce designer babies backfire and produce unhealthy offspring, then perhaps an *anti-eugenics movement* would arise.

By comparison, traditional norms and laws ban incest. I don't know if such norms and laws were motivated by negative effects of inbreeding.

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Norms and laws against incest aren't actually all that traditional. There have been plenty of societies where marriage within the family was common. Usually not the immediate family, but cousins, second cousins, etc.

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Indeed. European Royalty - and not a good advert. But the incest prohibition is more to do with fathers/daughters; mothers/sons; brothers/sisters. Also in large families as were, commonplace incest would mean breeding like rabbits. So economically unwelcome.

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Yes they were. I would say both from observation and low reproduction rate among inbreds. Our ancestors figured out the common factor.

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Bruce Schneier's book "Liars and Outliers", on trust mechanisms and how they fail, is relevant here. He has a brief discussion of the game theoretic model of Hawks and Doves: the key point is that a world of all Doves is not a stable equilibrium because the reward of being the first Hawk is too high.

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Perhaps politicians should have to take an MMPI, just like cops and firefighters. I asked my clinical psychologist wife more questions about this post and Michael Huemer's essay than just about anything else I have read here. In Huemer's essay he lists Trump and Ted Bundy as Psychopaths. Some of my questions to her were is Trump actually a psychopath, and not just a narcissist, and why isn't Trump killing people like Bundy then? To attempt to tersely and accurately summarize what my wife said about this and other things: You can't really look at a single trait or disorder of personality like that in isolation. All personality disorders are just more extreme versions of normal human traits. There are multiple traits and scales of personality interacting on each other. Trump is also a narcissist and narcissists actually care what other people think of them. Their image is intensely important to them. Bundy probably wasn't a narcissist even if he had a somewhat elevated level on that dimension. So Trump's narcissism may be one element actually tempering his psychopathy. I also asked her a lot about introversion and extroversion with relation to this and the distinctions between the cluster A,B, and C personality disorders and where they do and don't overlap.

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Homosexuality may just be a random mistake. I remember reading awhile back about fraternal birth order impact on rates of homosexuality. As the mother has more kids she generate more of a certain kind of anti-body, and the additional presence of that anti-body makes additional male children more likely to turn out gay. So this would be environmental, but environmental within the womb. And it would have a purpose, but turning kids gay wouldn't be the purpose, just a random byproduct.

I don't claim this explains all of homosexuality, but its a piece of the puzzle.

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Humans vary a lot. During an extreme shortage of resources, psychopathic levels of selfishness might be a significant survival advantage when pure altruism might result in *everybody* starving to death. Overall, yes, it would be a negative in a small group situation during normal times but it probably generates enough benefit during extreme deprivation to hang around at low levels. Even in normal times it could serve as a spur for exploration, raiding, and other high-risk but potentially high-reward activities. You could apply a similar theory to homosexuality being an extreme continuation to the normal level of same-sex affiliation necessary to promote cooperation among individuals. In a small number of folks that wiring just gets crossed with the reproductive drive.

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‘Would psychopathy have been selected against in small hunter-gatherer societies that have little surplus to steal? ’

Or maybe selected for? Psychopaths often possess high intelligence. Only a psychopath would have the callous disregard for others and the degree of elevation of self-needs to steal what little others had, and the guile and viciousness to take it, and certainly not share anything he had. More food, better able to provide, ruthless in self-preservation more attractive to female mates, therefore more successful at reproducing.

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RE: Homosexuality: If it is largely genetic (and I think it is) it doesn't need to disappear. Think of it as a highly recessive genetic trait, such that ~1-3% of the population tends to get it. It is still possible for heterosexual parents to have a homosexual child, some families or lines being more likely than others, just like the how the genetic lottery sometimes tosses up albinos etc.

Why do that? I suspect it is related to why women go through menopause: an extra adult to take care of the extended family while not having their own children to compete for resources can be very valuable to family members who do have children. In the case of older women, the dangers of child birth are outweighed by the value of accumulated knowledge, stabilizing matriarchal authority and just having someone else to help with the work and family tasks. A homosexual sibling or cousin provides extra resources to the extended family, increasing the survivability of the heterosexual member's kids without competing for them. Essentially extra human capital for the family. Too many and overall child production suffers, but a low rate could be very beneficial.

Considering how many social animals have groups with only one breeding female and many workers supporting them, it makes sense that humans would have some tendency towards that. Naked mole rats, Ethiopian wolves, meercats, hyenas... lots of mammals follow that pattern to a greater or lesser extent, often when available resources are tight relative to the needs of offspring.

In the case where homosexuality is suppressed and homosexuals get married to stay under the radar and fit in, I expect the result is just far fewer offspring for the couple. Or more nuns and monks, maiden aunts, etc. in the society.

All in all, I wouldn't expect the rate of homosexuality in society to change much at the genetic level, but rather all variation tending towards the cultural acceptance and encouragement of it. Even then, I would expect that what you would be seeing is an increase or decrease in the open behavior related to homosexuality as opposed to the internal attraction to the same sex aspect. (That's a whole other can of worms, though.) Unless the society started killing off the extended family of homosexuals, I don't see how one would lower the incidence in a meaningful way.

One way genetic incidence might change naturally is if resource abundance changed such that a higher adult:child ratio was counter productive because it was easier to raise kids, and so just cranking out more babies was the best way to have more. Then again, it might still be beneficial to have the occasional non-reproducing family member to help compete for status within the tribe. My guess, however, is that if resources were so plentiful that producing enough to keep kids alive was so trivial that the number of adults contributing was irrelevant you would see population explode to the point where that was no longer the case, and get back to a larger number of adults needed to optimize child raising output.

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Ah yes, the gay uncles, like post menopausal women, are known to stay with their extended family, help around the house and take care of the children, instead of, say, moving out to live alone in the city.

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Are you under the impression we are talking about the modern day as opposed to the evolutionary past when humans lived in much tighter family groups?

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Minor quibble: as I understand it, the best-supported current theory is that homosexuality is not genetic, but epigenetic. That said, epigenetic modifications can still influence evolution, albeit much less reliably and efficiently.

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Possibly. I think it is a bit of both, and really hard to disentangle. That classic problem with studying humans as opposed to inanimate things: carbon atom don’t claim they are actually boron.

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We already have a neo-eugenics movement. Look at the abortion rates for Down syndrome children.

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https://jaymans.wordpress.com/2014/02/26/greg-cochrans-gay-germ-hypothesis-an-exercise-in-the-power-of-germs/

male homosexuality may be caused by some viral damage to a cluster of neurons in the brain at a young age. it's the most likely explanation of the one's ive seen.

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We don’t know much

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“Perhaps it operates too slowly”.

Not when there are large-scale, world-wide wars (WWI and WWII), or large-scale world-wide migrations (into the US in the 1800s and 1900s)?

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An interesting thought is the role religion will play in this. If a religion is anti-eugenic tech that will cause some strong selection on the religious.

Personally, I don't think any religion should be anti-eugenic tech as its harmful to the members to do so. At the same time, I think there should be a place for people who are "left behind" by those who have selected for better genes to go and feel appreciated and welcome. I'm not sure how you come up with a message for those people that both accepts them but doesn't condemn the tech.

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"Would psychopathy have been selected against in small hunter-gatherer societies that have little surplus to steal?"

In "The Goodness Paradox: The Strange Relationship Between Virtue in Human Evolution", Richard Wrangham argues that during early human evolution, human bands often had "chimp-like" members, unable to consistently co-operate and follow the customs of the group, e.g., trying to have sex with other members' mates. When things got bad enough, they would go out hunting or gathering with a group and not come back--and nobody would ask any questions. Even if they didn't steal, they were "negative marginal product".

Thus, evolution selects for the third of the things that Bryan Caplan says schooling signals (the three being intelligence, conscientiousness, and conformity).

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I'd bet a moderate level of psychopathy is selected for, however, even if they might be zero or negative marginal product members from the group perspective. Psychopaths are often good at mimicking normies well enough to get to by, after all. So long as you can stay below a threshold you might be able to have plenty of kids before things caught up with you.

On the other hand, a few psychopaths in the group might actually be beneficial. Maybe the group benefits from having some rather predatory bastards among them if those bastards spend their time preying on neighboring groups and bringing back some spoils. Or maybe you need a certain willingness to hurt people to be an effective judge or war lord? There is probably a balance there, where going too far towards psycho is a big problem, but not enough is too. You need some odd ones to do certain types of jobs or fill certain roles. Not too many, and not too odd, but definitely not normal people.

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Hard selecting against psychopathy might make people full soy boy.

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Particularly if it is social selection... psychopaths seem really good at making sure they are the ones doing the selecting.

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