Do you think it's fully cultural? I agree that it can partly be the case, but I ...

Do you think it's fully cultural? I agree that it can partly be the case, but I doubt that it would explain all of the difference for several reasons:

- Wikipedia cites the study that showed this effect for the brain size (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8675415/)

- IQ is known to be mostly genetic (see e.g. Pinker's "Blank Slate"), so it's unlikely (though not impossible) that the differences in IQ stddev are cultural

- Wikipedia cites another study that found similar effect in birds: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7423667/. This kind of difference could evolve due to different reproduction strategies for males and females.