I know. Your daughter was just born loving pink. Your son made "vrooming" noises as he exited the womb. In CAMD I have a chapter on nature versus nurture, but I also highly, highly, HIGHLY recommend these three books. They are essential for anyone who has essentialist (i.e., everything is down to gender, boys will be boys, girls will be girls) tendencies. All three are super-readable and scrupulously researched and disentangle nature (which is real) from nurture (which is huge) revealing how our assumptions about kids and gender may be undermining our sons' and daughters' potential. Pink Brain, Blue Brain: How Small Differences Grow Into Troublesome Gaps and What We Can Do About It by Lise Eliot
The Truth About Girls And Boys:Challenging Toxic Stereotypes About Our Children by Caryl Rivers and Rosalind Barnett
This one isn't out yet, but I just read the galley and was impressed. I love Rosalind Barnett's and Caryl Rivers' work.