Could this be the answer to why people stray?
While we don't like to tar all cheaters with the same brush, apparently that old cliché 'once a cheat, always a cheat' could actually be true - and there's scientific evidence to back it up.
According to AsapScience, cheating is in our genes, with dopamine, the pleasure hormone, playing a big part in the decision to stray.
50% of people who have the long allele variant of the dopamine receptor have cheated on their partner - while only 22% of people with the short allele variant have done the same.
Apparently, long allele folks are also more likely to give into pleasure-seeking vices such as excessive drinking and drug-taking.
And it's not only alleles which are to blame (bet you wish you paid more attention in Biology GCSE now, right?). According to science, money also plays a part, with men who make more money than their female counterparts more likely to cheat - but also, men who stay at home during the day while their wives work are also likely to cheat. We can't win.
Then, the most obvious one of all - emotional baggage can also be a reason why people cheat, whether they had a difficult childhood or a traumatic breakup.
Here are all the theories explained in one helpful video...
Do you think the theories are true, or are people fully in control of whether they cheat or not? Let us know @marieclaireuk