Nature vs Nurture

Trust is the central theme in the comedy movie series that started with Meet the Parents. In the sequel, Meet the Fockers, Jack the father-in-law steals a DNA sample from Greg to secretly test for a suspected hidden paternity.

But what if you could test for much more?

Garcia and others (2010) have recently published a study in which they found that the incidence in which one partner in a relationship cheats on the other, more than doubles when the cheating partner has a particular copy of a gene encoding for the dopamine receptor DRD4 (specifically having a form of the gene in which there are more than 7 repeats of a particular sequence in one section of the gene). And were are not talking about guppies here, were are talking about people.

Table 1. Percentage who report an extra-relationship sexual experience by DRD4 genotype (7R+ vs 7R-) (from Garcia and others. 2010).

This dopamine receptor has been turning up in all sorts of interesting behavioral studies. One other form has been associated with political liberalism as an adult, and yet another with Attention Deficit Hyperactivity Disorder.

Intriguing is the well established relationship between dopamine and two hormones (oxytocin and vasopressin). Oxytocin has long been called the "cuddle hormone" because seems to be involved in romantic love, while vasopressin has been labelled as the 'divorce gene,' because a particular receptor type has been linked to problems with pair-bonding (i.e., monogamy).

Perhaps the take home message here is that the old 'O GOD' (i.e., one gene, one disorder) idea is dead, as most biologists have known for a long time. Yes, human behavior is strongly influenced by genes, but it is an interaction of many genes that matter. Research is just beginning to untangle this and any interest in predicting behavior based on what is known now would be less reliable than the already completely unreliable lie detector.

Still, I wonder how the report of the DRD4 infidelity paper will be received. Will there be yet another sequel to Meet the Parents in which Jack has Greg tested for his DRD4 receptor sub-type. I did a quick search to see if any genetics companies were offering a test for DRD4. It seems not yet, but I'll bet it won't be long.

Reference

Garcia JR, et al. 2010. Associations between dopamine D4 receptor gene variation and both infidelity and sexual promiscuity. PLoS ONE 5(11): e14162.