An intriguing new study suggests that people are more likely to cheat on their partners in the 12 months running up to a “milestone” birthday.
Academics at the University of California and University of New York looked at the profile of those who were being unfaithful and found that those aged 29, 39, 49 or 59 (named 9-enders in the study) were more prone to infidelity.
The evidence was compiled primarily using data from Ashley Madison, a dating website set up for those seeking an extramarital affair.
They found that 950,000 of the men registered with the website were 9-enders – this was 18 per cent more than a random sample would produce.
There was a similar spike in infidelity among women who were coming to the end of a decade, although it wasn’t quite so pronounced.
The findings were published as part of a wider study, which examined the lifestyle changes that people are likely to make as they approach one of their “big” birthdays.
It will fuel the debate about the main reasons that people have affairs, with differing opinions about the environmental and genetic factors that make people more likely to be unfaithful.
While this study adds weight to the argument that factors such as growing older can be big influences, previous research by scientists in Australia claimed that the presence of specific genes made people more likely to stray.