Does Your Mate have the Cheating Gene?

By Anastacia Mott Austin

Men who can’t commit finally have found a scientific excuse for their behavior: it’s all in the genes, baby.

Researchers at the Karolinska Institute in Sweden released a new study, published in this month’s Proceedings of the National Academy of Sciences, which shows that men with one or two variants of a certain gene were twice as likely as others to report troubles in their marriages over the past year.

Hasse Wallum, a behavioral geneticist, and his colleagues were interested in an earlier study showing that a gene was responsible for one type of vole’s (a kind of rodent) tendency to mate for life and another type to mate with many different partners.

They wondered if the same gene could affect human behavior.

The Swedish team set up an extensive study involving 552 pairs of twins between the ages of 37 and 64, and looked at patterns in their relationships with family and spouses.

They took blood samples and examined the AVPR1A gene, which had been responsible for the vole behavior, in the men.

The AVPR1A gene is responsible for the fluctuation of a brain chemical called vasopressin, which controls blood pressure, but also regulates emotional interaction.

Halle and his colleagues found that men who had a certain gene variant (called an allele) named 334 were more likely to report difficulties in their marriages, especially in terms of emotional bonding. In addition, the spouses of men who carried allele 334 were much more likely to report dissatisfaction with their husbands and the relationships.

"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 Wallum to reporters.

Men who carried two copies of the allele were also twice as likely as men without it to not be married at all.

The study said that 40% of men carry either one or two copies of the variant gene, and that vasopressin affects men far more acutely than women.

Scientists are also studying the possible links between the variant genes, or vasopressin levels, in people with autism. Autism is a disorder marked by the inability to form emotional attachments, and affects far more males than females.

So does the future carry a home kit where one’s future mate can be tested for his ability to be monogamous and attached?

Walum says it’s not that simple, and that far too many factors influence how humans behave, including but not limited to their genetic makeup.

Still, it must be easier for men without this gene variant to have successful relationships, some would argue.

Others say that people should be able to access this kind of information, in order to be forewarned, so to speak.

"There are many ways this information [could] help a man and his wife when they marry," said Helen Fisher, a Rutgers University biological anthropologist. "Knowing there are biological weak links can help you overcome them."

Adds Fisher, "What this means is that some people will go into marriage with a stronger deck of cards. But there are people genetically prone to alcoholism who give up booze and make a good marriage."

"No one is saying biology is destiny."