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Comment by readams | Hacker News Reader

It's unlikely there's a gene that codes for being gay. Homosexuality instead is better thought of as more like why men have nipples. Obviously the nipples are not useful to the reproductive success of men, but genetics and natural selection are messy and there's likely no easy path to not having them in men while maintaining their function in women.

For homosexuality, the systems of sexual attraction in the brain need to tune to the gender somehow, and this is a system which, apparently, isn't 100% successful at aligning gender and sexual attraction. So the answer to "why are some men attracted to men" is the same as "why do men have nipples:" it's because women need to be attracted to men and because women need nipples.

And of course it needs to be said that just because someone's sexual attraction isn't aligned to their gender it doesn't mean that they're inferior. We don't measure the worth of a person by their reproductive success.

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> We don't measure the worth of a person by their reproductive success.

We don't measure human worth that way, but evolution measures nothing else!

Nature does not measure things, has no purpose and no goals, success nor failure.

Imagining success, failure, and purpose is psychological projection.

On the other hand, the extiction of our species for not-reproducing would be quite a failure even on our own metrics.

So it's not like we're some higher-dimensional ethereal beings, not tied to evolution and our natural fitness, with relation to our successes and failures as a species (and even as individuals).

To reverse the "psychological projection" trope, it's just that we learned throu psychological denial to ignore those aspects most of the time...

No - evolution doesn't place a value (or worth) on reproduction at all.

Kin-selection hypothesis also allow for some fraction of asexual or homosexual population being a positive overall (from an evolutionary perspective).

Right. Selfish genes don't necessarily need to be beneficial for every individual that carries them. Queen bees have evolved -- through regular Darwinian evolution -- the trait of having a majority sterile offspring. Those genes don't help the worker bees, but they help the queen and so get passed down.

If you have a genetic mutation that means 1/4 of your offspring won't bear their own children, but will increase the likelihood of your grandchildren living to adulthood, that may well be something that gets selected for.

Not saying that this is necessarily the case with "gay genes," simply that it is perfectly consistent with standard evolution.

There is good evidence that gay males are much more involved with their neices and nephews [0] and that their sisters are more fertile[1].

[0] https://www.advocate.com/news/daily-news/2010/02/05/study-su...

[1] https://pubmed.ncbi.nlm.nih.gov/15539346/

I've seen this hypothesized and studied before as how homosexuality exists in the face of evolution. That is, some combination of (a) without children of their own homosexuals are better able to help raise their other family members, (b) homosexuality is strongly correlated to higher fecundity of female family members, and (c) homosexuality is just a fluke in sexuality in general, similar to how other complex biological processes often have birth reflects related to some failure in each step of those processes.

While the "fertile siblings" theory and evidence make a lot of sense to me, I also find it somewhat depressing, as if being gay is just kind of a fluke byproduct to help your other family members.

Yeah, evolution is a bitch. Never ascribe moral worth based on what evolution favours.

I think the theory makes more sense in communities in conflict. Missing fathers make the presence of an uncle much more important and high mortality rates make fertility rates more important.

Interestingly that somewhat overlaps (to my untrained eye) with cultures more accepting of homosexuality: early Japan, ancient Greece, modern tribal societies.

Do the numbers even add up? a whole extra child just to help out doesn't seem very efficient to me.

And it's only depressing if we define a person's worth by the number of children they have, so let's not do that :)

Not sure if nipples are the best analogy here. Formation of nipples is largely down to how fetuses develop; i.e. nipples form before sexual differentiation. And I believe in some mammals, males in fact do not have visible nipples.

https://www.livescience.com/32467-why-do-men-have-nipples.ht...

I'm not OP but maybe it's the same: attraction to men gets developed before sexual differentiation then gets (inaccurately) overwritten later?

Sexually antagonistic pleiotropy perhaps.

https://en.m.wikipedia.org/wiki/Antagonistic_pleiotropy_hypo...

I think this is called a Spandrel: https://en.wikipedia.org/wiki/Spandrel_(biology)

Umm... Men have nipples because they form before sexual differentiation occurs.

I don't see how this makes their illustration invalid.

This is, or could be, just the how not the why.

Here's the way you answer your question. Ask yourself, is this the answer I would have said in middle school? Or maybe, maybe high school. If you think the answer is worth more than that. Well... May god save your soul.

The recapitulation theory (Ontogeny recapitulates phylogeny) is based on observation. The tendency of creatures to develop in stages that roughly correlate as to how their ancestors evolved, is not related to sexual preference. There's no evidence that homosexuality shares the same root cause(s) as to why men have nipples, theoretical or otherwise.

But we do measure a person by their reproductive success. Where would one see otherwise?

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