Here's the biological reason why people cheat

A new study has found that hormonal reactions could be the reason why human beings are driven to cheat on their partners as well as commit fraud.

The research, published in the Journal of Experimental Psychology, looked at the biological traits underlying unethical behaviour to test the cheating-as-stress-reduction hypothesis, which is the idea that the body increases its production of the reproductive hormone testosterone to regulate and balance out the effects of cortisol, the stress hormone.

The Harvard University and University of Texas, Austin scientists found that not only do high levels of the two hormones mean a person is more likely to engage in a dishonest activity such as fraud, the endocrine-regulation system in the body reinforces bad behaviour.

The test subjects were given a maths test in which they self-reported how many they got right - but were told that the more they got correct, the higher the monetary reward would be.

Saliva samples tested collected before and after the test was administered showed that people with elevated testosterone levels overstated how many answers they'd got right.

Elevated testosterone decreases the fear of punishment while increasing sensitivity to reward. Elevated cortisol is linked to an uncomfortable state of chronic stress that can be extremely debilitating... Testosterone furnishes the courage to cheat, and elevated cortisol provides a reason to cheat.

• Dr Robert Josephs, University of Texas at Austin

So there we have it: next time you get caught doing something you shouldn't, there's no need for an excuses - human biology just gave us a get-out-of-jail-free card.

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