"Once a cheater, always a cheater" has got to be the most over-used and frankly tiresome relationship warning. It's drilled into us from the moment we start dating: If your SO bangs someone else behind your back, chances are they'll do it again.
Some reformed cheaters may argue this is complete BS, but we've all known someone who just can't keep it in their pants. There's got to be a scientific reason why they're a shameless serial cheater (otherwise, they're just really crappy human beings).
A new study has actually linked dishonesty and the brain, meaning there could be a legitimate reason why people cheat over and over again.
Elite Daily reported on the research, titled "The brain adapts to dishonesty," which found with every lie a person tells, they feel less guilty about it. We have an area of the brain called the amygdala, and it's hard-wired to produce a negative response when we lie. But that response becomes weaker every time we tell a fib.
Neil Garrett, co-author of the paper and researcher at the Princeton Neuroscience Institute, told Elite Daily:
"The idea would be the first time we commit adultery we feel bad about it. But the next time we feel less bad and so on, with the result that we can commit adultery to a greater extent."
Essentially, most of us don't cheat because we'd feel really bad about it. For serial cheaters though, every time they do it, they care less.
The findings could also be taken to mean that seemingly insignificant lies could lead to bigger, more destructive dishonesty in the future. Basically, learn to spot the signs and always tell The T.
Follow Paisley on Twitter.
This article originally appeared on Cosmopolitan.com/uk. Minor edits have been made by the Cosmo.ph editors.