Dubious news of an infidelity gene
More adventures in the "My genes made me do it" department, this time,
marital infidelity. Researchers at the Karolinska Institute, in Stockholm, have
concluded that men with that men with two copies of a particular gene variant
are less likely than men without it to be engaged in happy monogamous
relationships. Just over one-third of the men with two copies of the gene
variant had marital difficulties, but only 15% of the men with no copies
exhibited such difficulties. The gene in question regulates levels of the
hormone vasopressin. Studies have shown that this turns highly promiscuous male
meadow voles into model monogamous husbands.

The researchers reached the cautious conclusion that "previous studies on the
influence of the gene coding for the vasopressin receptor on pair-bonding in
voles are probably of relevance also for humans."

The media always find news of an "infidelity gene" exciting. In 2004, a
British researcher claimed that some women may be genetically programmed to
stray in their relationships. In a study of twins, he found that if one had a
history of infidelity, the chances her sister would also stray were about 55%.

However, Erik Parens, of The Hastings Center, an American bioethics institute
poured cold water on these suggestions. "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.)" The weak results of this
study, he argues, show that the One-Gene-One-Disorder (or O GOD) model of human
behavior has been discredited. ~ San
Francisco Chronicle, Sept 10; London
Times, Sept 2

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Michael Cook

Michael Cook edits BioEdge, a bioethics newsletter, and MercatorNet, an on-line magazine whose focus is human dignity. He writes from Sydney, Australia.

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