According to a recent study of 821 gay, straight and bisexual men published in the Archives of Sexual Behavior, a very significant minority of straight guys—like, 21 percent of them—have watched gay porn in the last six months.

Martin J. Downing, lead researcher, says he was not surprised by the results, noting that there is a ton of research documenting that men who identify as heterosexual can and often are attracted to other men. He says male sexuality is more fluid than many would care to think. Porn is fantasy, and fantasies do not dictate sexual orientations or identities.

There’s also the fact that straight porn focuses heavily on well-endowed guys getting off. If a man finds pleasure in watching that, it’s not unlikely that he’ll be inclined to watch porn that is all about male arousal.

Male sexuality is more fluid than many would care to think. Porn is fantasy, and fantasies do not dictate sexual orientations or identities.

But we live in a society that believes women are inherently more sexually fluid because… male homophobia and the hyper-sexualization of women on women. Of course, many women are sexually fluid and do watch a lot of lesbian porn—in fact, that’s what they watch the most, according to Pornhub. But I’ll go ahead and attribute that to the very unsexy jackhammering in straight porn, which makes lesbian porn more realistic, even for a lot of straight women.

And while news about straight guys watching gay porn may come as a surprise to many people, it’s also not totally new information. In 2015, Pornhub looked into their gay male content and found that the proportion of its visitors had grown 45 percent from 2012 to 2016. As of May, over three percent of all U.S. Pornhub visitors go directly to the gay male section of the site.

It’s just that now we know a large portion of those users are straight dudes.