Why do some people go through life without sex?
A new study of nearly 400,000 adults in the UK and 13,500 in Australia suggests genetics may play a role.
Researchers found that thousands of common genetic variants contribute to the likelihood of lifelong sexlessness, with links to traits such as education, intelligence and health.
Why sexlessness matters for health and evolution
Sexual relationships shape health, social life and over generations, reproduction. Researchers have linked a lack of intimate partnerships to worse mental health and social isolation, and argue that lifetime sexlessness, having no sexual partners, is a blunt but informative proxy for ancestral reproductive failure.
Past work on people who report never having had sex, otherwise called “virgins”, has been useful but limited. Many studies used younger samples, making it hard to tell delayed debut from lifelong sexlessness. Others examined a narrow set of traits (religion, employment, substance use) or focused on heterosexual intercourse, mixing behavior with sexual orientation.
What was missing was a large, older age sample with genetic data. The new study combined ~400,000 UK Biobank participants with an Australian cohort to run a genome-wide analysis of sexlessness. The goal: to quantify how much common genetic variation contributes to never having had sex, and how that genetic signal overlaps with cognition, personality and health.
Genetic study of sexlessness reveals heritable patterns
The study drew on two large datasets: the UK Biobank, which included around 400,000 people of European ancestry aged 39 to 73 years, and an independent Australian sample of ~13,500 adults aged 18 to 89 years.
The team ran a genome-wide association study (GWAS), scanning 10.6 million genetic markers. They built polygenic scores – measures of someone’s overall genetic tendency towards a trait – and tested these scores across the Australian cohort, and looked at genetic correlations, which show how much sexlessness shares genetic influences with other traits.
Genetic differences explained ~17% of the likelihood of sexlessness in men and ~14% in women. The overlap between the two sexes was only moderate, meaning men and women share some, but not all, of the same genetic influences.
“This is quite interesting, because for most behavioral traits the genetic correlation between men and women is much higher,” Dr. Karin Verweij, corresponding author and a behavioral geneticist at Amsterdam University Medical Center (Amsterdam UMC), told Technology Networks.
“In our phenotypic analyses, we found that sexlessness in men was more strongly associated with health, physical strength and the ability to form confiding relationships. Since these traits also have a heritable component, it is plausible that genetic factors influencing physical strength, for example, partly explain the genetic vulnerability in men, whereas this pathway may be less relevant in women,” Verweij added.
The GWAS flagged two significant genetic sites, although each only had very small effects.
Verweij and the team used ancient DNA, showing that one variant linked to sexlessness steadily declined in frequency over the past 12,000 years, “which is consistent with natural selection acting against it,” said Verweij.
When applied to the Australian sample, the genetic scores predicted that people with higher scores tended to start having sex later, had fewer partners and were more likely to report lifelong sexlessness, particularly among women.
“We found that genetic factors linked to higher intelligence were also linked to a greater likelihood of being sexless. This finding seems counterintuitive, as it challenges the theory that higher intelligence is associated with increased reproductive success,” explained Verweij.
“We have no obvious explanation for this finding. We speculate that maybe traits like conscientiousness may promote commitment to education or religion at the expense of seeking partners or that young adults with high educational potential avoid relationships that could interfere with their plans, and this pattern continues later in life,” said Verweij.
The study also compared sexlessness with childlessness and found substantial genetic overlap; however, sexlessness was more strongly linked to well-being and social connection.
Beyond genetics, sexlessness was tied to social and physical factors. Sexless individuals were more educated, used fewer substances, felt lonelier and unhappier and men in particular were more likely to live in regions with fewer women or greater income inequality.
Implications of genetic research on sexlessness
Sexlessness, like many complex behaviors, appears to have a measurable genetic component.
“Approximately 15% of the differences in sexlessness among people in later life appeared to be explained by thousands of genetic variants, each with a very small effect,” Dr. Abdel Abdellaoui, lead author and a geneticist at Amsterdam UMC, told Technology Networks.
Yet, the results also highlight how genetics intersects with social and cultural factors.
“Much of the genetic effects associated with sexlessness were shared with other traits, including a higher education and IQ, less substance use, higher autism and anorexia risk and lower ADHD, anxiety, depression and PTSD risk,” said Abdellaoui.
The results challenge the idea that intelligence evolved because it increased mating success. Instead, higher intelligence was genetically linked to a greater likelihood of sexlessness.
However, the study has limitations. The results show correlations, not causes, and the authors caution against talking about “genes for sexlessness.” The analyses were confined to people of European ancestry, so the results may not hold in other populations. Sexual history was also self-reported.
“It is important to note that in this study we could not distinguish between voluntary and involuntary virginity and these findings do not carry any value judgments,” Dr. Laura Wesseldijk, co-author and assistant professor at Amsterdam UMC, told Technology Networks.
Future research will need larger, more diverse samples and methods that can test causality. Distinguishing asexuality from difficulty finding partners will be essential. Another avenue is comparing sexlessness and childlessness to better understand how reproductive strategies interact in both modern and evolutionary contexts.
Reference: Abdellaoui A, Wesseldijk LW, Gordon SD, et al. Life without sex: Large-scale study links sexlessness to physical, cognitive, and personality traits, socioecological factors, and DNA. Proc Natl Acad Sci USA. 2025;122(38):e2418257122. doi: 10.1073/pnas.2418257122
About the interviewees:
Dr. Karin Verweij is a behavioral geneticist, interested in unravelling the roots of individual differences in human behavior. Verweij completed her PhD in 2012 at the Genetic Epidemiology Laboratory of the Queensland Institute of Medical Research, Australia. She has since worked as a geneticist at various universities, both in the Netherlands and abroad (Sweden, Australia). In 2018, Verweij was appointed professor of genetics in psychiatry at Amsterdam University Medical Center.
Dr. Abdel Abdellaoui is a geneticist who has been involved in a wide range of studies on psychiatric genetics, behavioral genetics and population genetics. Abdellaoui is an assistant professor at Amsterdam University Medical Center, where he is particularly interested in how collective behaviors, such as migration and mate-choice, influence the genetic make-up of populations and the relationship between genetic risk factors and environmental exposures.
Dr. Laura Wesseldijk is an assistant professor in psychiatry at the Max Planck Institute for Empirical Aesthetics in Frankfurt, at the Behavioral Genetics unit in collaboration with the Department of Psychiatry at Amsterdam University Medical Center. Wesseldijk obtained her PhD in 2018 at the Biological Psychology Department of the Vrije Universiteit in Amsterdam, where she studied genetic and familial factors that influence the development and persistence of childhood psychopathology. Wesseldijk’s interest and expertise lie in the field of behavioral genetics, mental health and musical engagement.