The authors explain that human sexual behavior varies considerably, not only between different populations, but also within them. Even though evolutionary theory is rooted in sexual behavior and sex-related characteristics, scientists do not know much about how genes affect individual differences in how we behave sexually.
Justin Garcia and team set out to determine whether DRD4 could have an impact on the motivation (compulsion) behind some sexual behaviors, such as infidelity and promiscuity.
181 young adults were interviewed regarding their relationships and sexual behaviors. Samples (buccal wash) were taken for DNA testing.
77% of those interviewed said they had a history of sexual intercourse.
The researchers found 50% of those with 7R+ - a genetic variation of DRD4 - had been unfaithful to their partner, compared to 22% of these without 7R+.
The impact of 7R+ on infidelity and/or promiscuity in males and females appeared to be about the same.
"What we found was that individuals with a certain variant of the DRD4 gene were more likely to have a history of uncommitted sex, including one-night stands and acts of infidelity.
The motivation seems to stem from a system of pleasure and reward, which is where the release of dopamine comes in. In cases of uncommitted sex, the risks are high, the rewards substantial, and the motivation variable - all elements that ensure a dopamine rush."
The relationships are associative, the scientists stressed. In other words, some people with the genetic variation will not be unfaithful or promiscuous, and some people without the variation will be.
As the relationship is associative, "The study doesn't let transgressors off the hook,", Garcia added.
So it may still be a bit early to blame it all on one's genes.
The same genetic variation has been linked to gambling addiction, alcoholism and a love of horror films.
"Associations between Dopamine D4 Receptor Gene Variation with Both Infidelity and Sexual Promiscuity"
Justin R. Garcia, James MacKillop, Edward L. Aller, Ann M. Merriwether, David Sloan Wilson, J. Koji Lum
PLoS ONE 5(11): e14162. doi:10.1371/journal.pone.0014162