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.
I reckon at this rate, by 2100 more than 6400% of highschoolers will be queer