Dating & Relationships

Once a Cheater, Always a Cheater? Here’s What the Science Says

September 18, 2017 by Justin Lehmiller

Is it a bad idea to get romantically involved with someone you know has committed infidelity in the past? Common sense tells us that “once a cheater, always a cheater.” However, it’s dangerous to rely on common sense to understand sex and relationships because research doesn’t always back it up and also because different people can hold very different “common sense” beliefs. We need to look instead at what science says about whether past infidelity predicts future infidelity,

This is the subject of my latest column over at TONIC. In it, I describe the results of a new longitudinal study published in the Archives of Sexual Behavior. Researchers tracked hundreds of people over five years, surveying them repeatedly about their relationship experiences. As a result, they were able to look at whether cheating in earlier relationships was linked to cheating in later relationships.

What they found was that people who had sex outside of an early relationship were nearly three-and-a-half times as likely to do the same thing in a later relationship. People who didn’t cheat the first time around were far less likely to do so in the future.

That said, it’s important to note that only about half of the people who had sex outside of their relationship repeated this behavior later on, which tells us that “once a cheater, always a cheater” is clearly an overly broad generalization. In order to understand when “once a cheater, always a cheater” is likely to hold and when it isn’t, we need to look at people’s motivations and reasons for cheating in the first place.

For complete details on the study and more on people’s reasons for cheating (and what those reasons mean for future infidelity), check out the full article over at TONIC.

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Image Source: 123RF/Andriy Popov

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Written by
Dr. Justin Lehmiller
Founder & Owner of Sex and Psychology

Dr. Justin Lehmiller is a social psychologist and Research Fellow at The Kinsey Institute. He runs the Sex and Psychology blog and podcast and is author of the popular book Tell Me What You Want. Dr. Lehmiller is an award-winning educator, and a prolific researcher who has published more than 50 academic works.

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