Our Genes Do Not "Make Us Do It"

There s an old saying: “The devil made me do it.” The modern iteration of this I-can’t help-myself-excuse is: “My genes made me do it.” This idea was boosted in a report recently that men with a certain gene variant were twice as likely to commit adultery as men without it. Erik Parens, a bioethicist at the Hastings Center Report, writes about this in today’s San Francisco Chronicle. From his column:

First, it’s possible to have the gene variant but to have no marital difficulties. (66 percent of the men with two copies of the variant had no marital trouble.) Second, it’s possible to have marital difficulties but not have the gene variant. (Again, 15 percent of the men with no copies of the variant did have trouble.) So, taking the results at face value, if you’re a man and have the variant, you’re surely not automatically in trouble—and if you don’t have the variant, you surely might still be unfaithful. Indeed, in their own argot, the authors of the PNAS piece explicitly acknowledge that their gene variant has “a relatively small effect size.”

The idea of single gene behavioral determination, Parens’ explains, is dead.

It’s not that genes are irrelevant in behavior:

Decades of comparing identical and fraternal twins show that the aggregate effects of multiple genes are indeed important in explaining the emergence of virtually all complex diseases and traits.

I think the words “virtually all” overstate the case, but even if that is true; we have to be careful. One of the unique aspects of human beings is our free will. As a vivid illustration, were I to ever stray on Secondhand Smokette and said, “Honey, it’s not my fault. My genes made me do it,” knowing Debra, she would nod, smile in empathetic understanding and say, “Honey, it’s not my fault, but my genes just expressed to produce an irresistible urge to pull a Lorena Bobbitt!”

We may have propensities, say for addictive behavior, but unlike animals, we are not slaves to our urges and instincts. We have the power control ourselves, although it may be difficult, or to give vent. This is one way in which we are exceptional. Genes, mixed with environment, may create urges and desires. But we are free. And with freedom, comes responsibility and accountability.