There's evidence that toy preferences of girls and boys are in part hardwired (http://www.ncbi.nlm.nih.gov/pubmed/18452921). It's analogous to career choices. It's what we all know intuitively, but political correctness pressures us to invent alternate explanations. Even esr succumbed: http://esr.ibiblio.org/?p=2118#more-2118.