A new paper was recently published in Nature [1] that provides insights about the gender gap in STEM.
The main outcome of the study, encompassing 2.6mln first grade students in France, is that a few months of schooling create a significant gap in Maths tests between male and female pupils.
There are no signs of correlation with the socio-economic background, meaning that the only possible variable to explain this gap is cultural and it has to do with schooling.
[1] Martinot et al. “Rapid emergence of a maths gender gap in first grade” https://www.nature.com/articles/s41586-025-09126-4