Teenage girls do worse in their education, careers and social lives when they have more high-achieving boys in their classes, according to a new study by two Cornell economists.

Teenage girls with greater exposure to boys who do well academically do worse in math and science and are less likely to go on to complete bachelor’s degrees, according to the research. In the long term, they’re less likely to work and more likely to have a child before they turn 18, the research suggests. Boys, on the other hand, are not affected by high achievers of either gender.

The paper, “Girls, Boys and High-Achievers,” was issued April 1 as a working paper by the National Bureau of Economic Research.

“Much to our surprise, we found that girls are going to be penalized by exposure to high-achieving male peers, whereas boys are not affected at all by high-achieving peers of either gender,” said co-author Eleanora Patacchini, professor of economics and associate department chair. Her co-authors are Angela Cools, M.A. ’18, a doctoral candidate in economics who will join the faculty of Davidson College in the fall, and Raquel Fernandez of New York University.

The mechanisms at play are tricky to tease out, said Patacchini. “But we do find some indication that these girls seem to have lower self-confidence and are more engaged in risky behavior, even including teenage pregnancy,” she said. “There seems to be something going on in terms of lowering their aspirations.”

In the study, the authors write: “Faced with a greater proportion of ‘high-performing’ boys, girls may become less self-confident about their own ability in traditionally male-dominated fields such as math and science. More generally, these high school girls may become more discouraged or think themselves less competent which could then affect their actual performance.”

The effect was most pronounced for girls with lower abilities and with at least one college-educated parent, she said. They are more likely to complete vocational or associate degrees, rather than bachelor’s degrees.

On the other hand, girls who had lower ability, who did not have a college-educated parent and who went to school in higher quality schools are more likely to get bachelor’s degrees and get better grades in school if they are exposed to high-achieving female peers. “These girls are the ones who actually benefit the most from the social environment,” Patacchini said. “So girls seem to help other girls.”

The researchers analyzed data from the National Longitudinal Survey of Adolescent to Adult Health, a nationally representative longitudinal survey of students in grades 7-12. The survey examined data from students at a representative set of 132 schools in the U.S. beginning in the 1994-95 school year. Students answered questions about their gender, age, race, parents’ education level, academic performance, and risky behaviors such as alcohol and drug use, unprotected sex and criminal behavior. They took a similar survey several years later.

The research team defined “high-achieving” using the education level of the students’ parents because it is determined prior to students’ meeting peers. (Students with parents who have high levels of education usually have better GPAs.)

In their paper, the scholars didn’t address policy changes that could help mitigate the detrimental effects of having more high-achieving boys in class. However, a potential recommendation could be to place an equal number of high-achieving girls and high-achieving boys in a given grade, Patacchini said.

“Certainly, given these results, one possibility would be to just equate the exposure.”

Funding for the research came from the CV Starr Center.