Gender Differences - Real or Assumed?

I was having a discussion with a family member yesterday about gender differences, and what I might write about on my next blog post.  The issue raised was that perhaps we are seeing some differences in genders because we are expecting to see the differences.  Maybe they aren't really there.  This made me step back and think for a minute.  I am sure this is not completely true.  That is, I am sure that there are some actual differences between genders.  But I think there is quite a bit of truth to the concept that we have preconceived notions about what it is to be a woman and what it is to be a man.  Some of these preconceptions date back a very long time.  Could it be that we are now conditioned to see things a certain way, but the reality is those differences are not really there?  For example, yesterday we talked about whether or not men felt threatened by intelligent women.  Could it be that we think men feel this way, so we assume it is true.  So when we see men, we are looking for confirmation of our hypothesis that they feel threatened by women.  As such, we see really only what we are looking for.  Then when we see it, we say, "see"!  What are we missing when we look at men and their views of women, and vice verse?  Have you noticed a bias in how you view the opposite gender?