The same gene that affects a rodent’s ability to mate for life may affect human marriages as well according to Swedish and U.S. researchers. One genetic difference seems to explain why one species of vole formed strong pair bonds for life, while another mated promiscuously.
Men carrying a common variation of a gene involved in brain signaling were more likely to be unhappy in marriages.
Although they are not sure what the genetic changes do to a man’s behavior, research suggests it has to do with the ability to communicate and empathize with spouses. Note that the study did not actually study infidelity statistics, only bonding with partners.