Identical twin studies point away from genetics very hard. Pretty much all genetic anomalies will affect both identical twins 100% of the time. The fact that it's less than 40% points much more to environmental effects rather than genes.
Study here : https://pubmed.ncbi.nlm.nih.gov/9549243/
"We present an overview of behavioral genetics research on homosexual and heterosexual orientation. Family, twin, and adoptee studies indicate that homosexuality and thus heterosexuality run in families. "
Baseless theories: people do this to feel better about LGBT discrimination or the idea of sexuality being out of our control is too scary for dudes who haven’t come to terms with their own masculinity. The latter isn’t necessarily shade, I’m not sure I figured it out until my mid-20s.
And yet, it's the other commenters who seem backwards to you?
Parent wants to push the "fixed gender" case instead.
I'm sure you can surmise the implications of this. Evolutionary biology has been making steady gains in the "nature not nurture" department and it has become an absolute lighting rod to discuss.
I don't really like these appeals to motive; this is quite an interesting empirical question that's disconnected from discrimination. Even if it would turn out that homosexuality is a choice (I don't think it is, but let's assume it would be) then this wouldn't change my position one iota. People choose whether to smoke weed or not, and I also think people should have the freedom to choose to do so.
I'm not so sure what the evidence says on this, but it appears it's less of clear-cut "it's 100% genetic" than it seems to be. These things are notoriously hard to study.
The real problem seems to be that people are afraid that the "God hates fags" people will run with these kind of things, but these people will do their thing anyway no matter what the science says on account of being homophobic twats.
As I pointed out in my other comment[1], I definitely chose to have gay sex at some point and certainly could have chosen not to. I don't think it's so black/white.
I've always found that somewhat offensive, because it somehow takes the sub/unconscious opinion that being gay is defective: "You wouldn't discriminate against someone with a severe birth defect, well gay people can't control it either." Fuck that. Whether it comes about from the genes, or through the environment, or most likely through some combination of the two, it is completely illogical for anyone who has ever felt sexual attraction of any kind to argue that it can "controlled", so I don't need some appeal to "it must be in my genes" to make me feel better.
On a related note, I don't see that the is it a choice? question is even meaningful in the first place. Preferences aren't generally something we get to choose. I could probably learn to like some unfamiliar genre of music simply by listening to a lot of it, but you could offer me a heap of money to like the PHP programming language and I'd still be unable to do so. My opinion of it isn't something I can so easily will to change.
21% of Monozygotic twins are left-handed when the other is right-handed. This is higher than the general population.
Aren't there plenty of genes that just lead to higher causes of something? There are identical albino and non-albino twins.
I'm really skeptical that albinism is environmental. But stranger things have happened, I suppose.