Scientific research seems to suggest that if you get caught cheating, you can blame it on your genes, your income, or the person you cheated with.
Yeah, that'll wash!
At five: Cheating is apparently a good evolutionary strategy. The basic object of evolutionary biology, scientists say, is that you can produce offspring that are strong enough so that your genes, in turn, get passed on by them.
Both men and women, theoretically, can benefit therefore from mating with multiple partners as it diversifies their genetic line.
Psychologists have argued that there must have been a lot of pre-histotic cavemen and women getting a little something on the side, as this explains why the gene pool is so full of 'cheater genes'. More on that later...
At four: Mate poaching is a pronounced trend. This is the practice of trying to lure someone away from their relationship in the hope that they start one with you. In one international study, nearly 70 per cent of people said they believe they have been the target of a mate poacher.
At three: Our brain gives us mixed messages. Neurology claims that our brains have evolved three systems related to love. One is for romantic love, the next is for long-term partner attachment, and the final one - relevant here - is for the sex drive: to make babies with a variety of partners.
Trouble is, these systems could all be working at the same time. So, while you may be attached to your partner and baby, you might also be attracted to someone else.
At two: Even happy spouses cheat, because of genetics. One study found that as many as 56 per cent of men and 34 per cent of women rated their marriage as happy, yet they still cheated.
One study in 2008 theorised that a specific gene was at a work, and men that possessed this gene generally had unhappier spouses, increasing the chances of infidelity.
Finally, at one: Economically dependent spouses are more likely to cheat. Research suggests this is true for both men and women. However, non bread-winning men were found to be three times as likely to cheat as women - whereas men who earn 70 per cent of the household income are the least likely to stray.