"If they're evolutionary mutations, then they must a have a physical component. I would love to hear your explanation as to what these physical processes are, and which gene, or genes, code for them."
Oxytocin is a hormone that is involved in (among other things) the bonding between a mother and her newborn. The gene # is A00048.
http://srs6.bionet.nsc.ru/srs6bin/cgi-bin/wgetz?-e+[TRRDGENES4-AC:A00048]