To add to their body of research (where adultery occurs worldwide, and when during the year), Illicit Encounters has published data regarding the average age of adultery.
They should know, as they claim to be the UK's leading married-dating website (apparently), with more than a million registered users.
According to the study, people are most likely to cheat on their partners when their age ends in the number nine (e.g. 19, 29, 39, 49).
Presumably there's something about coming to the end of a decade?
'The Danger Age'
The "danger age" is 39, when, according to data, people are almost twice as likely to cheat.
But just behind came 29 and 49, for similar reasons of vulnerability, change and lifestyle re-evaluation.
However, as the Huffington Post points out:
The Illicit Encounters’ research may not be unbiased: the company is financially backing the study, methods were not vetted by outside experts, and it was not peer-reviewed.
Nevertheless, this theory is supported by 2014 research from Adam L. Alter at New York University, and Hal E. Hershfield the University of California.
The respective studies investigated the behaviour of adults at "9-ending-ages", using data from a similar adultery-dating website, and calculated that there were proportionately 18 per cent more "nine-enders" registered on the site.
It's worth considering that users of dating websites aren't under any obligation to list their real age.
A spokesperson for the website told the Sun:
Our research shows that some people cheat to get their partner’s attention.
If their partner’s a workaholic or unavailable to them, being caught with someone else is a way of saying: ‘Hey, if you love me, pay attention to me!’
‘Payback cheating’ is also common. If you’ve cheated in the past or done something else to hurt your partner, they might retaliate to get even.
So if your partner is turning 39 this year, and you've been unfaithful, prepare for...