Why 'once a cheater is always a cheater'

A team of researchers has come up with an explanation as to why do people cheat, suggesting dopamine and vasopressin may be responsible.

Around 57 and 54 per cent of men and women admitted to cheating at least once, according to data collected by the US Journal of Marital and Family Therapy, the Independent reported.

Therapists and psychologists have attempted to decipher the myriad reasons for unfaithfulness, but there is some evidence the chemicals in our brains are responsible, AsapScience have claimed.

A 2002 study examined the length of almost 200 volunteers' dopamine D4 receptor gene, the neurotransmitter that controls pleasure in the brain.

It claimed 50 per cent of individuals with the long allele variant of the gene had cheated on their partner, compared to just 22 per cent who possessed the shortened variety. In addition, those with the longer variety were more likely to be risk takers and displayed addictive traits.

There is another chemical at play when people cheat: vasopressin.

This hormone, similar to oxytocin (released during sex and sometimes referred to as the 'cuddle hormone'), was examined in a 2014 Finnish study which found individuals who admitted to cheating that a gene variation that repressed the hormone below normal levels.