This still suffers from an unaddressed element of external factors. Including 60 participants who are athletes does not undo social pressures. Those athletes are still and were subject to social pressures throughout their childhood and adolescence. The same could be said for the men in the study as well. They were still disproportionately encouraged towards activities that would build grip strength.

There are other studies showing a more moderate bell curve overlap (closer to 50% of men studied have stronger grip strength than all women studied). I'd be interested to see data aggregated from different nations comprising individuals from similar age and height ranges across different continents. Taking a bunch of people still within western society as your sample base does, well, nothing to account for the inherent influence of western society on women.