Twin studies find reason you cheat on your partner could be written in your DNA

Are we doomed to repeat the mistakes of our parents? Well, according to science, we might be.

If your parents were cheaters or infidelity runs in your family, you might have inherited genes that make it more likely for you to be unfaithful in your relationships.

Multiple studies dating back two decades have shown strong associations between inherited genetics and the likelihood a person may cheat on their partner, which could be rooted in evolution. 

Dr Madeleine Fugère, a social psychologist at Eastern Connecticut State University, reviewed three major studies on the topic involving thousands of people from around the world. 

Based on her analysis, she concluded the research 'suggests that infidelity has a strong genetic link.'

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She wrote for Psychology Today: 'Infidelity has a genetic basis because in our evolutionary history, it was advantageous to pursue alternate partners in order to potentially increase the number of offspring.'

One study reviewed by Dr Fugère from 2004 was among the first to explore the issue.

The research, by epidemiologists at St Thomas' Hospital in London, suggested the heritability to cheat had as strong a genetic component as inheriting high blood pressure. 

The team surveyed 1,600 women, all of whom were either fraternal twins - who share half of their DNA - or identical twins - who share all of their DNA - to find out who amongst them had cheated on their partners. 

Results showed 21 percent of identical twins and 23 percent of fraternal twins had been unfaithful - defined as having sex with someone other than a husband or partner while married to or living with that partner.

To determine if cheating had a genetic link, researchers compared the concordance between each group. Concordance is the scientific term to describe similarities between two groups.

It is often used to refer to the presence of the same trait in both members of a set of twins. 

In this case, if both twins in the survey had cheated on their partner, they showed concordance. 

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If the identical twins had a higher rate of concordance than the fraternal twins, the researchers could conclude their behavior was related to their genes, since identical twins share 100 percent of their genetic code and fraternal twins only share about 50 percent. 

And the study found there was a higher rate of concordance in the identical twins - meaning one identical twin was more likely to be unfaithful if their twin had previously been.

The researchers therefore concluded the tendency to cheat could be about 41 percent inherited. 

In other words, having certain genes can effect up to nearly half of a person's likelihood to cheat. The other 59 percent that influences whether or not a person will cheat comes from their environment, according to the study. 

A 41 percent heritability is similar to how likely you are to develop migraines, depression and high blood pressure, the study's author Lynn Cherkas said.

The next study Dr Fugère analyzed was performed by psychologists at the University of Queensland on 7,378 sets of twins from Finland in 2015. 

They used the same techniques as the 2004 study to determine if there was a genetic link to being unfaithful.

Researchers found the link to cheating was even stronger than earlier studies had suggested. 

The team determined cheating for men could be 63 percent attributable to genetics. For women, that number was 40 percent.

'Our research clearly shows that people's genetic make-up influences how likely they are to have sex with someone outside their main partnership,' Dr Brendan Zietsch, who led the study, told the Economic Times. 

None of the researchers have pinpointed one for-sure 'cheating gene.' But many suggested it could be related to some of the genes associated with risk taking. 

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The third study reviewed was performed on a set of 181 unrelated students by researchers from the University of Binghamton and University of Georgia in 2010. 

The team collected surveys from the students about their infidelity and took oral swabs to perform genetic analysis. 

They found the students who had a certain variation of a gene, called the dopamine D4 receptor gene, were 50 percent more likely to have cheated on their partner. 

This gene plays a role in the brain's pleasure system and has been linked in previous studies to pleasure-seeking behaviors like drinking alcohol and eating. 

Given the high correlation between people with the gene who have the inclination to cheat, researchers concluded that infidelity could be linked to having this certain type of dopamine receptor. 

However, having this gene doesn't mean you are doomed to cheat on your partner, study author Justin Garcia said, because humans still have power over their own sexual choices, he told Newswise.

Garcia added: 'These genes do not give anyone an excuse, but they do provide a window into how our biology shapes our propensities for a wide variety of behaviors.'