This is probably tied to female "mathphobia" in some way, because in my experience males were the most competent math teachers. Gender biases notwithstanding, I can say there were three female teachers in my school career who influenced my math aptitude a great deal: my 1st/4th grade teacher (same woman), my sixth grade English/Computer teacher, my 10th grade Algebra 2 teacher.

What they all had in common was the ability to see my aptitude and find materials for me that I could benefit from. These teachers may not have been math whizzes, but they definitely weren't afraid to give their students material they weren't completely comfortable with themselves. They also encouraged me to do more difficult math and were very supportive in general. Their attitude carried me very far, even if they couldn't answer some of the more difficult questions I would ask. My calculus teacher was very good, but he was a gigantic asshole.