There is no fluidity as such. To gays, it was never a choice to be gay or be straight. It was always a chance to recognize an inner reality.
I agree with some of what you have said - maybe quite a good %, even - but what I have quoted is where these arguments start to fail, or at least fail to explain this adequately. For a few decades the gay rights people had most of society fairly well convinced that it was 'from birth'. Miley Cyrus (you can take 'pansexual' to start with) was the single biggest social influencer tearing that down at first, and then it came in droves and floods - because nowadays, we do, in fact, have all sorts of gender fluid, non gender, non binary and terms being bandied about that constitute everything *
BUT* a "I've been this way from birth" scenario. Miley's testimony, which clearly demonstrated sexual choices that had nothing to do with original, fixed biology - did more to tear down the "our condition starts at, and is fixed from, birth" claim than just about anything else had before that.
In other words, if the past 5-10 years had never happened, the "I've been this way since birth and cannot nor never had the opportunity to be any different" argument would have been pretty believable, since many people appeared to be living it out right in front of us. Then came the 50 other genders as well as the gender fluid, gender agnostic, gender different on different days and so much additional nonsense I feel it kind of called into question the whole thing.
Having said all that, I do believe and accept that some people are predisposed, probably either from birth or from a fairly young age - for reasons that I don't necessarily believe are always all biological, but also learned - to be homosexual.
So if the main gist of what you're arguing is that homosexuality isn't largely a conscious, adult choice, we could probably find common ground across that statement. But if you won't acknowledge the way that the last decade (or less) of the emergence of 1000 other versions of sexual deviations--many of which don't even CLAIM to be grounded in a "I was born that way" scenario at all, and in fact, do the exact opposite--Present a bit of a contradictory viewpoint--then our viewpoints diverge on that.
Beyond that, I could go into a long bit about what I have learned really happened with psychiatrists circa 1970's and how they were pressured to essentially give society what it wanted, rather than their true opinion about it being a mental disorder, and whether I think there were (magically) fewer gays when it was taboo, and more when it wasn't taboo, and what I think about what that obviously means as to pure biology vs. learned/permitted behavior......... but I don't want to seriously dig into all that since I know we disagree on that probably and don't wish to argue just to argue, although I do enjoy hearing other points of view.
