Women tend to act heroically within their own moral universe, regardless of whether anyone else knows about it - donating more kidneys to nonrelatives than men do, for example. Men, on the other hand, are far more likely to risk their lives at a moment's notice, and that reaction is particularly strong when others are watching, or when they are part of a group.
It is possible the world is divided into three genders - there are men, there are women and then there are women who choose to have nothing to do with children. How about men without children, he answered quickly, aren't they also different from fathers? She shook her head firmly, daring him to contradict her: no, all men are the same.