A hijack but curious - the average child has only some much intellectual capacity to divvy up. When they put more attention in one area well another gets less. (The early walker is often a slower talker, and the converse.) How much of the cause is discouraging math in girls relative to boys, vs a positive bias/expectation that girls will be more advanced in social and language skills? It seems like there is a gap favoring early grade level girl verbal skills, including reading, that is even larger than the boy math gap.