A study published in Sexuality & Culture has found that a substantial proportion of male college students who identify as heterosexual have kissed another man.

The researchers surveyed 442 men from 11 universities across the United States. They also conducted in-depth interviews with 75 male college students. All of the participants described themselves as heterosexual.

Forty percent of the participants reported having kissed another man on the cheek, while 10% reported having kissed another man on the lips.

Alcohol consumption was related to kissing another man, and participants who were involved in all-male competitive sports or members of a fraternal organization were more likely to have kissed another man.

“A few of the guys in the frat have been known to kiss each other when drunk, it’s become pretty normal now. We all know who the kissers are!” one participant told the researchers.

The study also found that those with more favorable attitudes toward gay men were more likely to have kissed another man.

Some of the participants said they did not consider kissing to be a sexual act. “I kiss [my friend] because I love him. I’m not attracted to him like that, but I do love him,” one student explained.

While for others, the opposite was true. “I consider it to be an intimate thing, something I’d only do with a significant other. That crosses boundaries that aren’t anything to do with gay. I wouldn’t even do it with a female friend because that’d just be weird,” a participant told researchers.

The findings indicate that “same-sex kissing between men is a behavior that can be engaged in while maintaining a heterosexual identity at these universities,” the researchers concluded.

The study, “A Mixed-Method Study of Same-Sex Kissing Among College-Attending Heterosexual Men in the U.S.“, was authored by Eric Anderson, Matthew Ripley, and Mark McCormack.