Edwina Currie reveals affair in her book in 2002
Edwina Currie – the former Conservative cabinet member – revealed that she had an affair with former UK Prime Minister John Major, while both were in office, in her memoirs in 2002 (Reuters)

Researchers believe they have found the gene associated with determining the odds on whether a woman will be unfaithful to her partner or not.

The gene at the heart of the study is known as AVPRIA, which affects sexual motivation and social behaviour, according to a Sunday Times report.

Particular versions of the gene are associated with "extrapair matings", as the researchers have characterised it.

Human beings carry two AVPRIA genes, one from each parent, resulting in a number of possible combinations.

Studies conducted on animals showed that some combinations of the genes are linked to promiscuity, leading to speculation that this behaviour could be similar in people.

"We find strong genetic effects on extrapair mating in women," suggested one scientist in a research paper published in Evolution & Human Behaviour.

Dr Brendan Zietsch, professor of psychology at the University of Queensland in Australia teamed up with geneticists and neuroscientists to look at both the DNA and behaviours of 7,378 men and women.

The studies found that 6.4% of women in the survey had been unfaithful in the previous year. A disproportionately high number of them were carrying particular combinations of the gene.

Zietsch and his colleagues expressed surprise as behaviour is controlled by many factors including social norms, opportunity, availability, number of potential partners and avoiding detection.

Men were more likely to be unfaithful than women, with 9.8% of those in relationships who admitted having had sex with other people in the previous twelve months.

Recent studies have indicated that female infidelity is on the rise. A University of Washington study found that those who earned $75,000 (£115,500) or more per year were 1.5 times more likely to have had extramarital sex than those earning less than $30,000.

Among the partners who cheated, 46% of women and 62% of men did so with someone they met through work.

However, many sociologists believe that other factors such as low relationship happiness and incompatibility in terms of sexual attitudes and values were predictive of infidelity.

According to the Kinsey Report Infidelity in Heterosexual Couples: Demographic, Interpersonal, and Personality-Related Predictors of Extradyadic Sex for women, relationship factors were more relevant to the prediction of sexual infidelity than marital status or religious beliefs.