This is no aberration. Immigrant girls consistently outperform boys, according to the preliminary findings of a just-completed, five-year study of immigrant children–the largest of its kind, including Latino, Chinese and Haitian kids–by Marcelo and Carola Suarez-Orozco of the Harvard Graduate School of Education. Though that trend holds for U.S.-born kids as well, the reasons for the discrepancy among immigrants are different. The study found that immigrant girls are more adept at straddling cultures than boys. “The girls are able to retain some of the protective features of [their native] culture” because they’re kept closer to the hearth, says Marcelo Suarez-Orozco, “while they maximize their acquisition of skills in the new culture” by helping their parents navigate it.

Consider the kids’ experiences in school. The study found that boys face more peer pressure to adopt American youth culture–the dress, the slang, the disdain for education. They’re disciplined more often and, as a result, develop more adversarial relationships with teachers–and the wider society. They may also face more debilitating prejudices. One teacher interviewed for the study said that the “cultural awareness training” she received as part of her continuing education included depictions of Latino boys as “aggressive” and “really macho” and of the girls as “pure sweetness.”

Gender shapes immigrant kids’ experiences outside school as well. Often hailing from traditional cultures, the girls face greater domestic obligations. They also frequently act as “cultural ambassadors,” translating for parents and mediating between them and the outside world, says Carola Suarez-Orozco. An unintended consequence: “The girls get foisted into a responsible role more than the boys do.” Take Christina Im, 18, a junior at Fairfax who arrived from South Korea four years ago. She ranks ninth in a class of 400 students and still finds time to fix dinner for the family and work on Saturdays at her mother’s clothing shop. Her brother? “He plays computer games,” says Im.

The Harvard study bears a cautionary note: If large numbers of immigrant boys continue to be alienated academically–and to be clear, plenty perform phenomenally–they risk sinking irretrievably into an economic underclass. Oscar Herrera, Martha’s dropout brother, may be realizing that. “I’m thinking of returning to school,” he recently told his mother. He ought to look to his sisters for guidance.