American researchers suggest a genetic element to an individual's sexual behaviour. A genetic variant of the dopamine receptor gene, DRD4, was found to be more common in people displaying higher rates of sexual promiscuity and infidelity.
'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', said Mr Justin Garcia, who led the study at the University of New York.
The neurotransmitter dopamine is associated with feelings of pleasure and satisfaction. It is released during activities that induce positive feelings, such as eating food and having sex, but also during risk-taking activities such as gambling. Infidelity and sexual promiscuity are thought to fall into both of these categories.
'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'', said Mr Garcia.
The study surveyed 181 university students on their sexual activities, as well as collecting samples of their DNA. Repetitive stretches of DNA called variable number tandem repeats (VNTR) were analysed. Students carrying one or more VNTRs in the DRD4 gene displayed more promiscuous sexual behaviours, such as one-night stands and showed a 50 percent increase in cases of sexual infidelity. The number of VNTRs in the DRD4 gene did not show any gender bias.
Mr Garcia pointed out that 'the study doesn't let transgressors off the hook. These relationships are associative, which means not everyone with this genotype (genetic make-up) will have one-night stands or commit infidelity. 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 behaviours'.
The study was published in the journal PLoS ONE.