sends in a New Scientist summary of research from Sweden pointing toward the existence of a gene that influences monogamy in men
. (The article doesn't mention women, and the study subjects were all men at least 5 years into a heterosexual relationship.) "There has been speculation about the role of the hormone vasopressin in humans ever since we discovered that variations in where receptors for the hormone are expressed makes prairie voles strictly monogamous but meadow voles promiscuous; vasopressin is related to the 'cuddle chemical' oxytocin. Now it seems variations in a section of the gene coding for a vasopressin receptor in people help to determine whether men are serial commitment-phobes or devoted husbands."