From the LA Times:

Girls have long embraced the stereotype that they’re not supposed to be good at math. It seems they may be getting the idea from a surprising source — their female elementary school teachers.

First- and second-graders whose teachers were anxious about mathematics were more likely to believe that boys are hard-wired for math and that girls are better at reading, a new study has found. What’s more, the girls who bought into that notion scored significantly lower on math tests than their peers who didn’t.

The gap in test scores was not apparent in the fall when the kids were first tested, but emerged after spending a school year in the classrooms of teachers with math anxiety. That detail convinced researchers that the teachers — all of them women — were the culprits.