Comparing to this Gallup poll of adult Gen Zers (18-25 year olds):
High schoolers: 26% LGBTQ; 12% bisexual, 11% questioning/other, 3% gay/lesbian
Gen Z adults: 21% LGBTQ; 15% bisexual, 3% questioning/other, 4.5% gay/lesbian
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They also found that, among all high schoolers that have had a sexual experience, 1 in 5 have had a same-sex experience (20%; 14% with both genders, 6% only with the same gender). Assuming that number will probably go up for them as they have more experiences.
And I feel like that's pretty interesting to note, because there's an annoying stereotype going around that most bi people, especially bi women, will only fall into opposite-sex experiences because they're a 1 or 2 the Kinsey scale. Obviously those people are valid too, but I don't think they represent the majority of bi people, and there's often some invalidation coming when people say that. I saw this study posted on Reddit, and people were like "it's probably just 99% straight kids looking for attention and trying to feel unique." That just isn't true.
Some anecdotal talk: I go to a progressive-ish college, and from my uni experience so far, I'd say like 1/4 of the people I became friends with at random (mostly guys) have ending up telling me they're LGBT in some form or another. And yeah, most of those people are bi.
Most bi people I know don't seem to have a preference at all, actually, a good chunk of them (including me) seem to have a preference for the same gender. I think I know one bi guy that says he only likes very feminine guys and enbies, so he's only been with girls so far. But other than that, all the bi people I know have either been with both main genders or only the same-gender! I had a talk with my straight friends actually, a lot of them said they have maybe a 5% same-sex attraction, but wouldn't identify as anything but straight because they can't see themselves with the same gender. I mean they could if they wanted to, that's probably an even much larger chunk of the population, but I'm assuming most people like that will keep identifying as straight.
Same with ancient Romans/Greeks I believe? People who were exclusive to one gender were actually sometimes considered pompous or picky. Dudes could fuck dudes all they wanted, although it was strictly expected that lower social class people bottom for upper social class people (very taboo for poor people to be the penetrators), so you had a lot bottomphobia tied to class, crazy enough. That and pedophilia, much like Pre-Meiji Japan.
hellenistic sexuality afaik was still quite focused on reproduction, "Dudes could fuck dudes all they wanted" but beyond classed/aged expectations of sexual roles, it was also expected that they'd marry & carry on the lineage.
which is why it's weird talking about 'gay' or 'straight' hellenistic people, since their baselines & definitions of deviancy were very different. it's quite difficult to say if someone like Alexander (who verifiably fucked men & women) was conforming to societal expectations or merely indulging what we would call bisexuality