Women were second class citizens by law up until 50 years ago in the United States and similar is true in most of the rest of the world. Women weren't allowed into Ivy League colleges or even in to any sort of upper education until relatively recently in human history. That this clearly had a profound effect on women developing math skills is the understatement of the year.
While I concur that there are mosaic features that are more common in one sex than the other, we don't know enough about the brain to know if those are innate or due to social factors like assuming that women are bad at math (which still to this day is culturally messaged to a lot of children).
In a 2011 study of math gender stereotypes in American elementary school children, two findings emerged. “First, as early as second grade, the children demonstrated the American cultural stereotype that math is for boys on both implicit and explicit measures. Second, elementary school boys identified with math more strongly than did girls on both implicit and self-report measures. The findings suggest that the math-gender stereotype is acquired early and influences emerging math self-concepts prior to ages at which there are actual differences in math achievement.” (emphasis mine) Even so, American girls are beginning to reach parity with boys in math.
https://www.pnas.org/doi/full/10.1073/pnas.0901265106
In regard to the first question, contemporary data indicate that girls in the U.S. have reached parity with boys in mathematics performance, a pattern that is found in some other nations as well. Focusing on the second question, studies find more males than females scoring above the 95th or 99th percentile, but this gender gap has significantly narrowed over time in the U.S. and is not found among some ethnic groups and in some nations.
Furthermore, data from several studies indicate that greater male variability with respect to mathematics is not ubiquitous. Rather, its presence correlates with several measures of gender inequality. Thus, it is largely an artifact of changeable sociocultural factors, not immutable, innate biological differences between the sexes. (emphasis mine)
Responding to the third question, we document the existence of females who possess profound mathematical talent. Finally, we review mounting evidence that both the magnitude of mean math gender differences and the frequency of identification of gifted and profoundly gifted females significantly correlate with sociocultural factors, including measures of gender equality across nations."
