Genes may influence twin divorce rates

American scientists have found that in marriages where one partner is an identical twin, the likelihood of divorce may be increased depending on the marriage status of the other twin.

Researchers at Boston university, Massachusetts, used the records of 8,000 twins drafted into the US army during the Vietnam war, who had been interviewed in 1987 as part of a survey into mental health disorders.

Looking at the divorce rates of identical and non-identical twins, the scientists found that a person's marriage was more likely to end in divorce if their identical twin's marriage had led to divorce. However, the same pattern was not found with non-identical twins, who only share half each other's genes.

Dr Michael Lyons, who led the research, said that the results were surprising, because it was not thought that inherited characteristics could affect something as complex as marriage longevity.

Marriage counsellors have been quick to point out that, although genes may play a part in whether or not a person gets divorced, other factors are also important. Marriage problems are often the result of unresolved communication difficulties between partners and it may be that the ability to settle disputes is inherited.

Julia Cole, a psychosexual therapist at marriage counselling organisation Relate, said: "Perhaps the gene gives some people a predisposition for being good at communicating, negotiating, having the ability to put themselves in their partner's situation and to change their behaviour for different situations."

She added that it was important not to think that a marriage will succeed or fail purely on a genetic basis. "People need to be in an environment where they are able to develop their inherited skills. Nature may be important, but so is nurture."

Interestingly, the incidence of marrying was not affected by whether or not a person's identical twin had married, suggesting that the decision to get married was based on environmental factors rather than genetics.

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Relate