But producing convincing evidence in this area is not an impossible task. For example, we can empirically assess the impact of the above mechanism by comparing the number of bright and very bright men and women who come from different cultural backgrounds.

I agree, and this was what I meant. Distinguishing between nature and nurture, as wedrifid put it, is a difficult but not impossible task.

Why is the placement of "burden" important? With this supplementary question: Do you know of evidence strongly suggesting that different cultural norms might significantly alter the predominant position of the male sex in academic mathematics?

I hope I answered both of these in my comment to wedrifid below. Thank you for bothering to take my question at face value (as a question that requests a response), instead of deciding to answer it with a pointless insult.