A gene variant has been linked with how well men feel they bond with their wives or girlfriends.

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STOCKHOLM: Scientists have confirmed what some women suspected all along: that marital woes can often be attributed to a man's genetic make-up.

A gene variant which is present in four of 10 Swedish men can explain why some men are more prone to stormy relationships and bond less to their wives or girlfriends, according to a study by researchers from the Karolinska Institute in Stockholm, Sweden.

"There are, of course, many reasons why a person might have relationship problems, but this is the first time that a specific gene variant has been associated with how men bond to their partners," said Hasse Walum, one of the researchers.

Male bonding

The team found that men who carry one or two copies of a variant of the gene often behave differently in relationships compared with men who lack the gene variant, called allele 334. "The incidence of allele 334 was statistically linked to how strong a bond a man felt he had with his partner," the researchers said.

According to the study, published this week In the U.S. journal Proceedings of the National Academy of Sciences, men who had two copies of allele 334 were twice as likely to have had a marital or relationship crisis in the past year compared with those who lacked the gene variant.

Their wives or girlfriends also noticed the difference. "Women married to men who carry one or two copies of allele 334 were, on average, less satisfied with their relationship than women married to men who didn't carry this allele," Walum said.

He stressed, however, that the effect of the genetic variation was relatively modest and could not be used to predict with any real accuracy how someone would behave in a future relationship.

Nature and nurture

The study surveyed 550 twins and their partners or spouses in Sweden. Martin Ingvar, a professor of neurophysiology at Karolinska Institute, said the results were "very exciting".

"These are original findings which shed light on the fact that all of our behaviours are influenced by both nature and nurture. Even complex, cultural, social phenomena such as marriage are influenced by a person's genetic make-up," Ingvar said.

The gene in question controls the production of a molecule receptor for vasopressin, a hormone that is found in most mammals. The same gene has previously been linked to monogamous behaviour in male voles, a mouselike rodent.

The researchers said they hoped greater knowledge of the effect of vasopressin on human relationships could also help with our understanding of diseases characterised by problems with social interaction, such as autism.