It's not being down-voted because it's not a valid discussion point, but instead probably just because HN has a very liberal audience.
Even the most educated are still capable of bias, and many here do not like the opinion that it is possible that women differ from men in any significant ways.
Don't take the down-votes too personally. As long as you are posting constructive feedback with some evidence to your hypothesizes they will be appreciated by many even if the vote count doesn't make it appear to be so.
