This shows a profound misunderstanding of evolution and natural selection on your part. "Evolutionary benefit" is impossible to divorce from circumstances. It doesn't exist as some right/wrong answer, or something you can divine through logic.
For instance, same-sex attraction could absolutely be advantageous to a species that is nearing the peak of sustainable population numbers. All species (who can fuck) wanna fuck, and will do so no matter their surrounding circumstances. The difference between one species keeping sustainable numbers, versus another species seeing runaway population numbers causing food source exhaustion and population collapse, could come down to lower procreation rates, in which circumstance strict heterosexuality may not be advantageous.
Point being, stop trying to use bad, dime-store "science" to justify your bad opinions about homosexuality.
Personally I suspect the issue here is that incest is the only form of sexual activity that we have a natural proclivity against, probably because of evolutionary pressure (as in, hard-wired into our DNA) against fucking blood relatives. Because a consistently-inbred population will breed itself into oblivion. People who fuck kids can still successfully reproduce and society trundles on.
There's a traditional view of sexuality that men are only sexually attracted to women, and vice versa, and that's normal and everything else is not normal (kinky). The more we learn about sex (and gender) the more we learn that there are very few completely "normal" people out there, and a lot of people who are a bit kinky in one respect or another. I think it's now accepted that the hetero-homo thing is a spectrum rather than a binary state, and the primary reason people of the same sex don't have sex with each other is societal pressure rather than biological attraction. e.g. women tend to experiment more with this because society has a more lenient view of "girl-on-girl" than male homosexual sex.
My personal opinion is that evolution "wants" everything to fuck everything as much as possible, just to see what happens. The best reproducers are the ones who did the most fucking, after all. But we're getting into Oglaf territory here.
It's a term rooted in the conditions that make sex a reproductive act and not just something that feels good
Why are you projecting your own biases into my statement? Call a spade a spade. What you take away beyond that is on you.
You grouped all sexual activity into two groups: "normal" and "not normal". I think if anyone is projecting bias, it's that.
it's not unique to nature. You're in heat, you want to mate with anything that looks attractive. What's attractive will vary immensely based on societal and personal experience, for reasons we still cannot fully understand as the human mind is still a huge secret to unlock. It's not perfect in the same way that few parts of nature are perfectly optimized. Remants of old patterns or general heuristics on "what is good enough" will remain and they can persist for very long times.
The only unique-ish thing about humans is that we have no "mating period". We are continuously in heat compared to most of nature, so that urge remains around consistently. Virtually every form of society has evolved some sort of culture to control these urges (as well as ways to control sexual conflict, which is another topic entirely) in order to advance as a civilization otherwise it'd be non-stop mating
Is it generally accepted that someone may not be born either straight or gay?
I can somewhat sidestep that issue and say that societal factors can make you think you are exclusively heterosexual, even if we agreed that sexuality is an internal factor and you were infact born bi/homosexual. Similar to how you can force a left handed person to become right handed.
Hence, paedophilia is classified as a mental illness, but homosexuality no longer is (in most Western countries, at least, I believe).
I contend that human sexuality is not easy to compartmentalize and that it does not exist in any particular way as an obvious evolutionary benefit except for adult-adult-heterosexual.
Of course rapists (including child molesters) should be kept from offending and otherwise punished for offenses because of the harm that it causes, but nothing about any sexual orientations seems strange to me that it exists.
Of course I am not able to understand on an innate level since I don't feel the same way. I'm not sure anyone could really understand what it is like to be of a different orientation because it is so intertwined with the self that it is just incomprehensible. One can understand in the sense that one can acknowledge it, but I don't think one can understand in the sense that they actually 'get' it.
I'm interested in other people's perspectives on this thougjh.