Liberals like to think of themselves as the party of science. That's why it's so interesting to see science increasingly undercutting core liberal beliefs.
This is most obvious in the field of gender difference. Liberals don't want there to be natural differences between men and women, because they don't want gender to count in defining who we are. Only self-created things are supposed to define us in the liberal belief system.
And yet science continues to show that liberals are wrong in their belief that gender difference is not natural but merely socialised. The latest evidence is a book by Steven Rhoads, an academic at the University of Virginia. This book reviews the scientific literature on the subject and finds that it "overwhelmingly establishes the case for nature - that is, for natural sex differences".
The review of the book by P. David Hornik gives a few examples of gender differences occurring in children from very young ages (in fact, even from a day old). (I've also written on this theme here.)