Polling numbers suggest that nearly 30% of Gen Z adults identify as queer. Of these, 15% are bi, 5% are gay, and 8% are something else.

I have seen widespread skepticism of these numbers: accusations that a lot of that 30% are really just heterosexuals faking it for attention. But I think these numbers are plausible, and that as more people grow up in gay-accepting environments we should expect more and more people to come out as bisexual.

Gay New York and Queer London are history books about queer men of the early twentieth century. Both books extensively document a peculiar pattern. Working-class communities distinguished a group of men known as “fairies,” “flamers,” “queens,” and several other names. Fairies had effeminate mannerisms and styles of speech, dressed stylishly,1 wore makeup, often used women’s names, and of course were exclusively attracted to men. Any observer can identify this subculture as gay men.

But “normal” men had sex with fairies. While it is impossible to know exactly how many normal men had sex with fairies, the historical evidence is unambiguous that it was quite common. And working-class men saw sex with fairies no differently than sex with female prostitutes. As long as the man took the male part (receiving oral sex and anally penetrating the fairy), he was considered entirely ordinary, masculine, and not “gay.” Some “normal” men in New York City even deliberately sought out sex with fairies, because they thought it couldn’t transmit sexually transmitted infections, because anti-venereal-disease campaigns in World War I had only talked about the dangers of sex with women. We have records of multiple psychiatrists who tried in vain to convince working-class men that they were engaged in sexually deviant behavior.

Or consider ancient Greece. We have copious historical evidence of widespread homosexuality in ancient Greece, especially relationships between adult men and teenage boys. Pornographic vases depict gay sex; Greek lyric poetry praises the beauty of boys and curses their fickleness; Aristophanes’s plays are full of jokes about horny boy-lovers. The Symposium, Plato’s classic dialogue on love, mentions only in passing the possibility that one might be in love with a woman. Two characters, Pausanias and Agathon, are adults who appear to be in a loving, long-term, committed relationship. In a later period, we have three surviving dialogues—Pseudo-Lucian’s Erotes, Plutarch’s Amatorius, and a passage in Leucippe and Clitophon—debating whether it is preferable to love women or boys. This debate implies that homosexuality is quite common, and that most people get to pick.

These are only two examples of cultures with very widespread, normalized male homosexuality.2 A number of other examples exist, from pre-Meiji Japan to Golden Age Islam. Further, situational homosexuality has been commonly observed in all-male environments from boarding schools to sailing ships to prisons. In short, I think that the balance of the historical evidence suggests that, if homosexuality is unremarked upon and completely unexceptional, a very high percentage of human men (and presumably women) will be bisexual.

To be clear, I don’t mean to imply that all people are bisexual. Conversion therapy failed horribly, which means that there’s a population of very motivated people who simply can’t become attracted to different-gender people however hard they try.3 Surely a similar (though perhaps larger) population exists of straight people who simply can’t become attracted to people of the same gender no matter how hard they try. All the historical evidence is consistent with there being a very large population of straightforward heterosexuals. It’s just not consistent with straightforward heterosexuals, invariably and across all cultures, being 95% of the population—or even 50%.

The real question is why so many people in our culture are straight. I can think of three reasons.