Andy DUbbin/Fusion

I was a late bloomer. I didn't have a boyfriend in high school, I didn't get asked to prom, and I didn't "hang out" with "friends" at the "movies." But I did get straight As.

I'm not saying the lack of male attention led to my academic achievement—but a new study published in the American Economic Journal: Applied Economics is!

After studying thousands of teens, economist Andrew Hill, an assistant professor at the University of South Carolina, found that high schoolers who have low shares of opposite gender friends tend to have higher GPAs. On the flip side, students who have high shares of opposite gender friends tend to do worse in school. Which makes sense—after all, opposite gender teen "friendships" are rarely just platonic, even if one party thinks so (see: every teen movie ever made).

Hill came to these conclusions after analyzing 8,435 students from 76 schools across the U.S. The data came from the National Longitudinal Study of Adolescent Health, a 13-year-long study that followed adolescents who were in grades seven to 12 during the 1994 to 1995 school year. The study continued to collect data through 2008 to measure longterm effects.

While in high school, students in the study were asked to list their same and opposite gender friends. If two people listed each other, the relationship was considered a "strong." (For example, if Jane said Sara was a friend, Sara would also have to list Jane as a friend for it to be considered "strong.") If a person was listed as a friend but the entry was not reciprocated, the friendship was considered "weak." In all, 68 percent of friendship nominations were matched.


Participants were then measured for their "share" of opposite gender friends. In other words, a male who has two male friends and two female friends has the same share of opposite gender friends as a male who has three male friends and three female friends. The ratio is unchanged. However, a male with two male friends and four female friends has a higher share of opposite gender friends.

(Hill chose to look at share instead of total number because two people with an even share of same and opposite gender friends—whether it was five of each or two of each—shared more commonalities than two people with the same number of friends but different ratios.)

The students were also asked how far apart they lived from their friends, how often they talked on the phone (it was the 90s), how often they met after school, how often they hung out on weekends, and how often they talked about their problems.


Hill then looked at students' GPAs, along with their individual grades across four subjects: Math, English, History, and Science. Congruent with previous studies, overall, females scored higher grades than males, as you can see in the chart below:

The number 4 represents an A, while 1 is a D or lower.

Hill also looked at how well students got along with their teacher, how distracted they were in class, and whether or not they had been involved in a romantic relationship, based self-reported data. Females were more likely to report being in a relationship in the last 18 months.


After examining all the data, Hill found that—drum roll, please—opposite gender friends "are shown to have a negative effect on high school performance." His findings held true even after controlling for other variables that can affect academic performance, including parent characteristics, home language, household income, family structure, and grade repetition. Ultimately, Hill says he's confident the link is causal, not just correlational.

Notably, Hill found that overall effect was three times larger for females than males.

Teen girls were particularly impacted when it came to achievement in math and science. As Hill put it, "adolescent females may shy away from competition and perform less well in mathematics in the presence of males." (Hill adds that this finding is on par with other research showing that girls have more to gain from single-sex classrooms than boys do.)


But the impact of opposite gender friends didn't end with GPAs. Teens with higher shares were also more likely to get in trouble with their teacher and struggle with paying attention in class. They were also more likely to have trouble getting homework done and getting along with other students, but to a lesser degree. Plain and simple, "Opposite gender friends are a distraction in class," Hill told Fusion. That, he said, was one of the biggest takeaways from his research.

Having a higher share of opposite gender friends also increased the likelihood of dating and entering into a romantic relationship in high school, which in turn had negative effects of its own. According to Hill, teen relationships "reduce both the quality and quantity of homework and studying, if students spend time with their romantic partners, as well as [distract] in the classroom."

But what about when these kids grow up? The study followed the students from 1995 all the way until 2008 to measure subsequent-year GPA scores, as well as whether they graduated high school, attended college, and got married.


Turns out, as a group, students with a larger share of opposite gender friends as performed worse in the first three categories—but they were more likely to be married. So there's that.

In the end, Hill views his findings as fodder for the ongoing debate around same-sex education. "Reorganizing classroom gender composition is a relatively low-cost policy," he writes, "as it need not require more teachers or resources."

Tell that to the horny teenagers "hanging out" at the "movies."

Taryn Hillin is Fusion's love and sex writer, with a large focus on the science of relationships. She also loves dogs, Bourbon barrel-aged beers and popcorn — not necessarily in that order.