Why don't people appreciate a scientific view of human uality?

I asked a similar question once and a very thoughtful GWS regular explained to me that if you are committed to a constructionist view of gender differences, then acknowledging biological differences must be understood to have little or no impact. It was pointed out that the biological explanations have, in the past, been used to argue for the primacy of the male gender, and thus, tend to be rejected. I totally disagree with the argument, but I do, at least, understand it.