Let me lay out some statistics that, considered together, seem quite improbable. First, 91 percent of college students agree that their lives are dominated by the hookup culture. Second, the median number of hookups for a graduating senior is seven. That’s fewer than two hookups a year. Only about 40 percent of those hookups include sexual intercourse so, technically, the typical student acquires only two new sexual partners during college.

If students agree with the rest of the panicked culture and the recent New York Times story that they are embedded in an alcohol-fueled, porn-soaked, party scene that welcome casual sex, how is it possible that their actual sexual activity can be described with numbers like two and seven?

This was the question that led me to rethink what was really happening on college campuses. The vast majority of published research on hookup culture, mine included, focuses on the gender dynamics: the extent to which college women are empowered or disempowered by their experience with hookup culture. Media coverage of the phenomenon has followed suit.

Gender, however, is not the only way to slice the data. Buried in the statistics is information about who is participating in the hookup culture more or less actively. And, it turns out, not everyone on campus embraces the scene equally. Only 14 percent of students hookup more than 10 times in four years and these students are more likely than others to be white, wealthy, heterosexual, able-bodied, and conventionally attractive, according to quantitative studies of hookup behavior. Students who do not fall into these categories hook up significantly less and are more likely to disapprove of or be uninterested in the whole endeavor. To give you an idea of why, I’ll briefly discuss what we know about the attitudes and behaviors of African-American versus white and working-class versus middle-class students.

African-American students are less likely to hook up than white students. Sociological studies suggest that lingering racism plays a part: Black people have been traditionally stereotyped as hypersexual (trigger warning: see the “jezebel” and “mandingo” stereotypes). So, for black men and women, embracing sexual freedom can bring individual rewards, but also risks affirming harmful beliefs about African-Americans. In response, some black people feel the need to perform a politics of respectability. Rashawn Ray and Jason Rosow, for example, in a comparison of black and white fraternities, found that black men’s resistance to negative racial stereotypes sometimes involved being “good” and following mainstream social norms of appearance and behavior.

There are other, more practical reasons as well. Unpublished research led by USC graduate student Jess Butler, whose dissertation addressed hookup culture, suggests that there may be a separate African-American hookup scene on some colleges. However, hookup scenes often revolve around fraternity houses and, because of historic and ongoing economic inequality, black fraternities are less likely to have houses. Meanwhile, in general, black students are more strongly in favor of gender equality and drink less alcohol than whites. Neither of these facts facilitate hookup scripts.

Working-class students are also less likely to participate in hookup culture. Upper-middle- and upper-class students approach college with a certain sense of entitlement. They hook up because they are fairly confident that they will spend several years working on their careers before they get married. And they feel confident that they’ll graduate from college with relative ease, so they’re comfortable spending a lot of time partying. Here’s an example of how one class-privileged college student sees things, as reported by sociologists Laura Hamilton and Elizabeth Armstrong:

“I’ve always looked at college as the only time in your life when you should be a hundred percent selfish … I have the rest of my life to devote to a husband or kids or my job … but right now, it’s my time.”

In contrast, poor and working-class students, who are often the first ones in their families to attend college, tend to take it much more seriously and don’t take for granted that they’ll finish, so they party less. They also bring their values with them, so they imagine starting a family earlier. Investing in a serious boyfriend or girlfriend is more in line with these goals. As one working-class student said, in a separate study by Hamilton, about her wealthier peers:

“Some of these girls don’t even go to class. It’s like they just live here. They stay up until 4:00 in the morning. [I want to ask,] ‘Do you guys go to class? Like what’s your deal? … You’re paying a lot of money for this … If you want to be here, then why aren’t you trying harder?’ ”

So what we are seeing on college campuses is the same dynamic we see outside of colleges. People with privilege—based on race, class, ability, attractiveness, sexual orientation, and, yes, gender—get to set the terms for everyone else. Their ideologies dominate our discourses, their particular set of values gets to appear universal, and everyone is subject to their behavioral norms. Students feel that a hookup culture dominates their colleges not because it is actually widely embraced, but because the people with the most power to shape campus culture like it that way.

Update, July 19, 2013, 10:50 a.m.: This article has been revised to add specifics and clarity.