Study finds genetic, environmental links to sexlessness in hundreds of thousands

More than 400,000 adults worldwide have never had sex, according to a large, multinational analysis that draws on data from hundreds of thousands of participants in the United Kingdom and Australia. The study examined 405,117 British individuals of European descent (218,744 women and 186,373 men) and 13,500 Australians, of whom 3,929 reported never having vaginal, oral, or anal intercourse.

Researchers evaluated 251 traits across domains such as mental health, sleep, exercise, substance use, risk-taking, cognition, general health and occupation. They found that 148 traits were significantly associated with sexlessness, with 35 traits explaining at least one percent of the variation. Among the most common associations were less frequent and shorter mobile phone use, fewer visits with friends and family, and reduced opportunities to be in a confiding relationship. Sexless individuals also tended to report feeling more nervous and lonely and less happy, highlighting a connection to emotional well-being.

Genetic analysis showed that genes accounted for roughly 15 percent of the variation in whether individuals had experienced sex. The researchers noted that the genetic analyses also enabled detection of genetic correlations with other traits analyzed in separate studies. They emphasized that regional and socioeconomic factors were influential: men were more likely to remain sexless in areas with fewer women and higher income inequality, suggesting that local social and economic environments shape sexual opportunities. The study authors described their approach as examining a range of correlations rather than proving causation.

Differences emerged between men and women. For men, factors such as grip strength, body measurements, income, snoring, mobile phone use, sense of life meaning, and having someone to confide in were more strongly linked to sexlessness. Among women, work-related factors like hours worked showed closer links to childlessness, while income and confiding relationships were stronger predictors for men. The researchers cautioned that some observed sex differences may reflect social and cultural patterns, including how men and women report sexual experiences.

The researchers stressed that the results do not pinpoint a single cause. They noted considerable uncertainty about what underlies the observed associations. Not having had sex could influence happiness, but unhappiness could also hinder the ability to find a partner; a third, unmeasured factor could cause both. The study also acknowledged that participants reported only whether they had had sex, not whether they had ever desired to have sex, leaving open the possibility that some sexless individuals may identify as asexual. The authors said the results likely reflect a mixture of voluntary and involuntary sexlessness and that some findings cannot be fully explained by asexuality, such as the link with local gender balance and lower male strength.

The study was published in the Proceedings of the National Academy of Sciences. Brendan Zietsch, associate professor at The University of Queensland, noted in The Conversation that early-age eyeglasses and other traits often stereotyped as “nerdy” may influence adolescent dating experiences and, in turn, adult romantic confidence. The researchers emphasized that the work represents correlations across a broad set of traits and should not be read as a simple cause-and-effect blueprint for why some people never have sex. They called for further research to tease apart voluntary choices, biological factors, and environmental influences in shaping sexual experiences.