[suizi]

I don't think it is entirely genetic. There are other factors like development within the mother's body, levels of hormones / chemicals, and so on which could contribute to a different sexuality later on.

This doesn't mean you can change it, and messing with chemical levels in the hope of finding a configuration which leads to "normality" would be very unethical in my eyes.

[NoImmatureAdHom]

This is the ingredient most of this discussion is missing. People here seem to mostly believe "If it's not genetic then it's nurture", but that's not the case. It can be all sorts of other things.

My (rusty) recollection of the literature is that our best guess for what most causes homosexuality in human males is the hormone profile given in utero. This is not caused by the fetus's genes, but it will interact with the fetus's genes. Hormone levels could be influenced by the mother's genes[0]

I think what HN-ers are really interested in is, "How much control can we humans practically exercise over this?", the answer being "very little" in both the case of "genes control sexual preference 100%" and "in utero hormone levels control sexuality 100%".

0: https://en.wikipedia.org/wiki/Maternal_effect

[strken]

Given the pretty strong birth order effects in play when it comes to gay men[0], you could probably stop about a quarter of the gay male population from being born just by banning consecutive male births, assuming you were willing to enforce a comically evil level of control over the population.

[0] https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male...

[dragonwriter]

> Given the pretty strong birth order effects in play when it comes to gay men[0], you could probably stop about a quarter of the gay male population from being born just by banning consecutive male births, assuming you were willing to enforce a comically evil level of control over the population.

A one-child policy with exceptions available if the first-born is a girl is a “comically evil level of control” that is hard to imagine being applied in the real world?

[zaarn]

A one-child policy is ethically achievable by making the parents rich or otherwise making retirement care a non-concern. If you look at studies, rich people or people who have retirement taken care of are more likely to produce less children. A socialised retirement plan along with a good safety net for those unemployed would likely drive down population massively within a few generations.

[strken]

I'm not a huge fan of China's one-child policy, no, and I'd be even less of a fan if they'd done it with the intent to eradicate gay men.

[dragonwriter]

> There are other factors like development within the mother's body, levels of hormones / chemicals, and so on which could contribute to a different sexuality later on.

Those could still be influences if it was purely genetic. Biological sex is approximately fully genetic (not quite, but very close to it), but womb environment (I remember pH differences specifically being identified as an influence) play a role in which sperm, with which sex chromosomes, are most likely to survive and reach the ova.

[Zardoz84]

https://en.wikipedia.org/wiki/Crocodile#Reproduction

On many complex species, the genere isn't defined by the genes.

[dragonwriter]

I meant “in humans”; yes, there are places where that isn’t the case.