I attended the local school board meeting on Monday night to hear an update on gifted education in my children's district (K-8 only). Our gifted programs start in 3rd grade with a pull-out for math and LA. I, along with board members, was surprised to hear from the director of gifted ed that there is a huge discrepancy in the number of boys vs girls in gifted math across the district -- 75% boys vs 25% girls. There is not a large difference for gifted LA, although girls outweigh boys. I feel like there must be some flaw in their math identification as the girls aren't being recognized.
A property of normal distributions is that even small differences in the means of two different normal distributions can produce large differences in the tails. A 3-to-1 sex ratio is not implausible if the gifted math program is very selective. What fraction of students are selected for the gifted math program? Where I live the middle school math team is closest thing to a gifted math program, and the sex ratio of students selected for math meets based on their scores in tryouts exceeds 3 to 1.