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Once a Cheater, Always a Cheater? DU Study Examines Serial Infidelity

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Lorne Fultonberg


Lorne Fultonberg


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Infidelity Study

If Kayla Knopp had her dream job, she’d be penning advice columns for the newspaper. If the University of Denver doctorate student's research is any indication, she would never be short on material.

After all, her recently released study, “Once a Cheater, Always a Cheater?: Serial Infidelity Across Subsequent Relationships,” contains some jarring findings. For one, 40 percent of unmarried couples report infidelity. Worse: cheaters are more likely to cheat with future partners. Worse still, those who are cheated on are even more likely to endure similar heartbreak.

“The past matters for relationships,” says Knopp, who will graduate with a PhD in clinical psychology in May. “What we do at every step along the way in our romantic histories ends up influencing what comes next — whether that’s infidelity or cohabitation or a bunch of other relationship behaviors. That history tends to come with them.”


Kayla Knopp
Kayla Knopp

As a researcher who specializes in romantic commitment, Knopp has read plenty of papers on unfaithful partners. What consistently went missing, she realized, was data on serial infidelity. In other words, will the cheat repeat?

Fortunately, Knopp had at her disposal five years of data compiled by psychology research professors Galena Rhoades, Howard Markman and Scott Stanley. With collaboration from this DU team, Knopp was able to track 1,600 individuals from relationship to relationship and examine their behavior. She found:

  • Someone is three times more likely to cheat if they have cheated in the past.
  • A person is two to four times more likely to be cheated on if they have been cheated on or have suspected cheating in a prior relationship.
  • Men and women are equally likely to cheat or be cheated on.
  • A person's likelihood of cheating is found, not in a single demographic characteristic, but in a complex combination of factors, including cultural values and available partners.

“Regardless of whether you are the perpetrator of the infidelity or whether your partner was, those experiences are substantially more likely to repeat themselves,” Knopp says. “However, there are lots of people who break those patterns.

“I don't want to suggest that it’s someone’s fault that someone is cheating on them, but I think it’s important to acknowledge that we all play a role in our relationships. For people that find themselves having that experience, it may be worth taking a look at whether they could do something to prevent that from happening again.”

Galena Rhoades
Galena Rhoades

As Rhoades, who is also a practicing psychologist, sees it, her findings are especially useful for her professional peers. In their work with clients, they may be able to spot signs that warn of future infidelity.

"The research points to how important it is that we talk with people about what their relationship experiences are and what they want to leave behind or take with them from those experiences into new relationships," she says. "Science like Kayla’s work can help people choose partners wisely and make their relationships better going forward."

Knopp looks forward to diving deeper into that science and examining the motivations behind serial infidelity.

“Hopefully, by identifying risk factors, then that gives people a little more power and control in their own lives,” she says. “That might be really important to discuss, so we can plan ahead to avoid unwanted outcomes in the future.”