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“Sex is like money; only too much is enough.” –John Updike. That may be true generally, but not everyone is wealthy, and some people never have sex. One percent of the adult population has never had any form of sexual experience. A new study finds that a reason for this is not in their jeans—it is in their genes.

The study by researchers publishing in the journal PNAS analyzed the genes of 400,000 people in the United Kingdom between the ages of 39 and 73 and 13,500 Australians, aged 18-89. They sifted through the data to find people who have never had any type of sexual experience with the same or opposite sex. This left them with a dataset of 2,068 sexless females and 1,861 sexless males. What they found is surprising.

Talk Nerdy to Me, a Turn On?

Sexual behavior is complex, and many factors are involved, but the study found a cluster of genetic variants that was strongly associated with having never had sex. Prominent among these are genes associated with intelligence.

If you presumed that genes producing brighter brains drive brighter bedroom activity, you would be as surprised as the researchers were. The opposite effect was found. Genetic associations with higher childhood IQ and higher education correlate with sexlessness in adulthood. The genes that boost cognitive function, and their associated traits, are also correlated with higher income and socioeconomic status. This puzzling finding applied equally to both sexless males and sexless females.

This negative correlation between smarts and sex seems counterintuitive from the perspective of natural selection in mating choices, which would seem to place a premium on mates with higher intelligence and richer resources. As the authors explain, “Obvious explanations for [this]…are not apparent to us.”

It seems that some aspects of human nature, the facts of life among them, remain elusive to the facts of science.

In correlating the genetic variants of sexless individuals with other factors, the researchers conclude that being nerdy negates opportunities for nookie. Having weaker physical strength, which they measured by grip strength, punier arm muscles, and wearing glasses at an early age, were associated with sexlessness in men. Wearing glasses as adults had no effect on sexlessness. Focus groups reported that sexless individuals with these genetic traits had experienced being called “nerds” and “geeks” as adolescents, and they perceived this as being unattractive.

Everyone Looks Good at Closing Time

Sex and alcohol go hand in hand. Couples meet at a cocktail bar. Alcohol, being a powerful solvent, dissolves inhibitions. Consistent with alcohol as an aphrodisiac, the study found that sexlessness was associated with less imbibing of alcohol, not smoking cigarettes, and not using cannabis. Engaging in these addictive behaviors is associated with genetic variations that promote risk-taking and pleasure seeking. A weaker drive for adventurous engagements may make people more reluctant to play the mating game. Sexlessness was also correlated with genetic variations associated with low extraversion. This would tend to make people less likely to engage in social situations, often where alcohol is served, where they could meet potential sexual partners.

Psychological Conditions

Other genetic variants associated with various psychological disorders were also associated with sexlessness. It is not surprising that certain conditions could make finding mates more difficult. Gene variants associated with attention-deficit/hyperactivity disorder, autism spectrum disorder, and posttraumatic stress disorder were correlated with sexlessness. Poor mental well-being can make attracting potential sexual partners more difficult, but genetic variants that predispose people to major depressive disorder and anxiety were negatively associated with sexlessness.

It is important to note that while the study reveals that there is a genetic predisposition to sexlessness, this only explains a small part of the reasons why people are sexless. Another factor that the study identified was men living in a region with fewer women. Sexlessness was also more prevalent in regions with higher income inequality. Moreover, sexual behavior is a personal choice, and while the study finds greater levels of unhappiness in the population of sexless individuals, some may simply prefer that lifestyle.

In a nutshell, the study shows that genes and environment influence having a lifetime without sex, but a bulging brain can put a cold shower on sex.

First published in Psychology Today