It's complementarity, and it's hogwash. There will always be more differences between individual people as people--taking into account background, ethnicity, religion, education, life experiences--than between people as male or female. Now that we have discovered epigenetics, we know that life experiences literally change DNA, so bio-fundamentalism is out. Even from a fundamentalist perspective, men and women are more alike than different. Our society has benefited tremendously from acknowledging this basic fact.