Men are more likely to be devoted and loyal husbands when they lack a particular variant of a gene that influences brain activity, researchers said – the first time that science has shown a direct link between a man's genes and his aptitude for monogamy.
The finding is striking because it not only links the gene variant – which is present in two of every five men – with the risk of marital discord and divorce, but also appears to predict whether women involved with these men are likely to say their partners are emotionally close and available, or distant and disagreeable. The presence of the gene variant, or allele, also seems predictive of whether men get married or live with women without getting married.
“Men with two copies of the allele had twice the risk of experiencing marital dysfunction, with a threat of divorce during the last year, compared to men carrying one or no copies,” said Hasse Walum, a behavioral geneticist at the Karolinska Institute in Stockholm who led the study. “Women married to men with one or two copies of the allele scored lower on average on how satisfied they were with the relationship compared to women married to men with no copies.”
The scientists studied men because the hormone being examined is known to play a larger role in their brains than in women's brains.
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The finding set off a debate about whether people should conduct genetic tests to find out whether potential mates are bad marriage prospects. Several independent scientists called the discovery remarkable and elegant but disagreed over whether such information ought to be used in making personal decisions about love and marriage.
Walum said that the presence of the allele increased the risk of conjugal discord, but that many other factors probably shape marital behavior. But he and other scientists said the study is the latest piece of evidence to show that biology – down to the level of individual genes – can play a powerful role in shaping complex human behavior.
In other words, if a man's culture, religion and family background each have a seat at the conference table that determines his attitudes toward marital fidelity and monogamy, his genes might well sit at the head of the table.
The study was published in the Proceedings of the National Academy of Sciences.