Asexuality is a sexual orientation characterized by little to no sexual attraction to others, and the honest scientific answer to “why” is that no single cause has been identified. Like other orientations, asexuality appears to involve a mix of biological, neurological, and possibly prenatal factors rather than a conscious choice, a traumatic experience, or a medical problem waiting to be fixed. Research in this area is still young compared to the decades of work on other sexual orientations, but the evidence that does exist points toward asexuality being a stable, naturally occurring variation in human sexuality with roots that likely begin before birth.
How Common Is Asexuality
The most widely cited prevalence estimate comes from a large national probability sample of over 18,000 British residents, which found that roughly 1% of the population reported no sexual attraction to a partner of either sex.1PubMed. Asexuality: prevalence and associated factors in a national probability sample That figure has become a common reference point, though it likely undercounts asexual people for a few reasons. The survey was conducted in the early 2000s, when the term “asexual” as an identity was far less widely known. It also used a narrow definition, asking only about sexual attraction and offering no room for gray areas. More recent surveys using broader definitions and allowing respondents to self-identify tend to produce somewhat higher numbers, particularly among younger adults who are more likely to be familiar with the term. Still, the 1% figure gives you a ballpark: asexual people are a small but real slice of the population, roughly comparable in size to some other well-recognized minority groups.
Sexual Attraction and Romantic Attraction Can Be Separate
One of the most useful concepts to come out of asexuality research is the idea that sexual attraction and romantic attraction are not automatically bundled together. Most people experience them as linked, so it is easy to assume they are the same thing. But interviews with asexual individuals show that many frame their attraction as “split,” meaning they experience romantic feelings toward others without experiencing sexual attraction, or vice versa.2Social Currents. Splitting Attraction: Differentiating Romantic and Sexual Orientations Among Asexual Individuals Research confirms that sexual and romantic attraction can exist independently of one another.3Sexualities. “I would ask people why they bother to date”: Evidence of the importance of romantic attraction in the development of sexual identity for asexual individuals
This distinction matters practically. An asexual person who identifies as romantically attracted to people of another gender might describe themselves as “heteroromantic asexual.” Someone who experiences no romantic attraction at all might call themselves “aromantic asexual.” These are not just labels for the sake of labels. Studies comparing romantic and aromantic asexual individuals find real differences in behavior and relationship patterns. Aromantic asexual people tend to identify more strongly with the asexual label and report more avoidant attachment styles. Romantic asexual individuals, by contrast, tend to have more past sexual experiences, engage in romantic relationships more often, and express more desire for future partnerships, sometimes including physical intimacy.4PubMed. Sexuality, Sexual Behavior, and Relationships of Asexual Individuals: Differences Between Aromantic and Romantic Orientation In other words, asexuality is not one monolithic experience. Romantic orientation shapes how it plays out in someone’s life in ways that are measurable and meaningful.
Neurodevelopmental Clues
Some of the strongest hints that asexuality has biological roots come from the same kinds of markers researchers have studied in other sexual orientations: handedness, birth order, and finger-length ratios. These traits are all influenced by the hormonal environment in the womb, so differences in them between asexual and non-asexual people can suggest that something in early development set the stage.
One study found that asexual men were about 2.4 times more likely to be non-right-handed than heterosexual men, and asexual women were about 2.5 times more likely to be non-right-handed than heterosexual women. The same study found differences in the number of older siblings between groups, and these effects depended on handedness.5PubMed. Biological markers of asexuality: Handedness, birth order, and finger length ratios in self-identified asexual men and women A more recent study found a similar pattern, with asexual men showing elevated rates of non-right-handedness compared to non-asexual men.6The Canadian Journal of Human Sexuality. Exploring digit ratio and handedness in asexual and allosexual individuals
Why does handedness matter? Being left-handed or ambidextrous is linked to differences in brain lateralization that are partly shaped by prenatal hormone exposure. The fact that this pattern shows up in asexual populations suggests that the conditions in the womb may influence not just the direction of someone’s sexual attraction but whether they experience it at all. This does not mean handedness causes asexuality or that every left-handed person is asexual. It means these traits share some of the same developmental origins, and that is useful information for understanding what asexuality is at a biological level. Interestingly, neither study found significant differences in digit ratio (the relative length of the index and ring fingers), a marker that has been linked to prenatal testosterone exposure in other contexts. So the picture is not perfectly tidy, and much more research is needed.
What Twin Studies Suggest
Twin research is one of the classic methods for untangling genetic and environmental contributions to a trait. For sexual orientation broadly, studies of identical and fraternal twins have found that identical twins are roughly twice as likely to share the same sexual orientation as fraternal twins. But about a third of identical twin pairs still end up with different sexual identities, even though they share the same DNA.7PubMed Central. Sexual Orientation in Twins: Evidence That Human Sexual Identity May Be Determined Five Days Following Fertilization That gap suggests genes contribute but do not fully determine outcome. Other factors, possibly including the timing of embryo splitting or differences in the uterine environment, may play a role.
No large-scale twin study has focused specifically on asexuality, which is a significant gap in the literature. But the broader twin findings on sexual orientation are relevant. They support the general picture of orientation as something with a genetic component that interacts with prenatal conditions, rather than something purely learned or chosen. Researchers have speculated that whatever biological processes contribute to the variation in who people are attracted to could also produce the outcome of attraction to nobody, but this remains an open question that dedicated studies have not yet answered.
How Asexuality Differs from a Medical Disorder
One of the biggest misconceptions asexual people face is the assumption that their lack of sexual attraction must be a symptom of something wrong. Low sexual desire can be a feature of conditions like hypoactive sexual desire disorder, and a related diagnosis called sexual interest/arousal disorder. But asexuality and these clinical conditions are different in important ways.
The most critical difference is distress. Clinical diagnoses of low desire require that the person be bothered by it or that it cause problems in their life. Most asexual people are not distressed by their lack of sexual attraction. They are distressed, if at all, by other people’s reactions to it. Research comparing people who score high on asexuality measures with people who have clinically low desire finds that the asexual group is less likely to experience sex-related distress. They are also more likely to have never engaged in sexual activity, fantasy, or even kissing, not because they are avoiding something unpleasant but because the interest simply is not there.8PubMed. Asexuality: an extreme variant of sexual desire disorder? Research has also noted that no study has directly compared how asexual individuals and women with sexual interest/arousal disorder respond to sexual stimuli at the level of initial attention, highlighting how under-studied the distinction still is.9PubMed Central. Asexuality vs. sexual interest/arousal disorder: Examining group differences in initial attention to sexual stimuli
This matters because asexual individuals sometimes encounter healthcare providers who try to diagnose or treat their orientation as a dysfunction. A medical journal review aimed at clinicians has noted that asexuality should be understood as a sexual orientation rather than a pathology, and that asexual individuals often face misunderstanding and pressure within healthcare settings to identify a sexual dysfunction.10PubMed Central. Asexuality If you are asexual and a doctor suggests hormone tests or therapy to “fix” your low desire without first asking whether it bothers you, that is a sign the provider may not be up to speed on current understanding.
Does Asexuality Change Over Time
A common question asexual people get is whether they will “grow out of it” or “just haven’t met the right person yet.” The research here paints a nuanced picture. One longitudinal study following young adults across two survey waves found that most people who reported no sexual attraction in one wave did not report the same thing in the next wave, with only three out of 25 maintaining that response. The consistency was lower than for other sexual minority identities.11PubMed Central. The Temporal Stability of Lack of Sexual Attraction Across Young Adulthood On the surface, this seems to suggest asexuality is unstable.
But context matters. That study measured a single survey item about attraction, not a self-chosen identity. A different study that tracked people who actually identified as asexual found that roughly 83% maintained that identity between adjacent survey waves. People who reported low sexual attraction, low desire for partnered sexual activity, and high identification with asexuality tended to stay asexual. Those who changed were more likely to have reported higher levels of sexual attraction and desire from the start, suggesting they may have been in a questioning or transitional period rather than firmly asexual.12PubMed. Stability and Change in Asexuality: Relationship Between Sexual/Romantic Attraction and Sexual Desire The researchers concluded that these findings support treating asexuality as a relatively stable orientation. So while some fluidity exists, as it does for other sexual orientations, the evidence does not support the idea that asexual people are simply in a phase.
The Overlap with Autism
One of the more consistent findings in asexuality research is a statistical link with autism. Multiple studies have found that people on the autism spectrum are more likely to identify as asexual or to report low sexual interest compared to neurotypical populations.13PubMed. Are Autism Spectrum Disorder and Asexuality Connected? Going in the other direction, a study of people on the asexual spectrum found an autism prevalence of about 6.9%, which is considerably higher than general population estimates.14PubMed Central. Sexual, Romantic, and Community Experiences of Individuals at the Intersection of Autism and Asexuality Research on young autistic women specifically has also confirmed this elevated rate of asexual self-identification.15PubMed. Brief Report: Asexuality and Young Women on the Autism Spectrum
The reasons for this overlap are not fully understood. One possibility involves sensory processing. Many autistic people experience sensory input differently, sometimes with heightened sensitivity that can make physical touch overwhelming rather than pleasurable. Studies have found that autistic individuals detect certain odors at significantly greater distances than non-autistic people, reflecting broader differences in how the brain processes sensory information.16PubMed Central. Enhanced olfactory sensitivity in autism spectrum conditions If your sensory system processes touch, smell, and closeness more intensely than average, sexual contact might be unappealing on a purely sensory level regardless of any emotional or romantic feelings.
Another possibility is that the same neurodevelopmental variations that produce autistic traits also influence the brain systems involved in sexual attraction. The handedness findings discussed earlier are consistent with this idea, since non-right-handedness is also elevated in autistic populations. It is also possible that social differences associated with autism, such as less conformity to social expectations, make autistic people more willing to recognize and label their asexuality rather than performing sexual interest they do not feel. These explanations are not mutually exclusive, and researchers suspect all of them contribute to some degree.
Trauma, PTSD, and What the Data Actually Shows
Perhaps the most sensitive question around asexuality is whether it can be “caused” by sexual trauma. A study of U.S. college students found that asexual individuals were more likely to report both a PTSD diagnosis and a sexual trauma in the preceding 12 months compared to non-asexual students.17PubMed Central. The Co-Occurrence of Asexuality and Self-Reported Post-Traumatic Stress Disorder Diagnosis and Sexual Trauma Within the Past 12 Months Among U.S. College Students This finding is real and should not be dismissed. But interpreting it correctly requires some care.
Correlation does not tell you which came first. An asexual person who is “out” may face increased vulnerability to certain kinds of boundary violations precisely because their orientation is not taken seriously. People who do not display expected sexual interest can become targets for “corrective” sexual aggression. The study’s own design, measuring trauma within the past year among people who already identified as asexual, makes it impossible to say whether the trauma preceded the identity. And the broader research on asexuality’s stability and neurodevelopmental markers argues against trauma as a primary cause for most asexual people.
None of this means that trauma cannot affect someone’s experience of sexual desire. It clearly can. But the clinical and research consensus is moving firmly in the direction of treating asexuality as an orientation with biological underpinnings, not as a trauma response. If you are asexual and also have a trauma history, both things can be true simultaneously without one being the explanation for the other. A therapist familiar with asexuality should be able to help you work through trauma-related issues without treating your orientation as the problem to solve.
Minority Stress and Mental Health
Asexual people face a specific kind of social pressure that researchers call minority stress: the cumulative toll of being misunderstood, dismissed, or actively targeted because of your minority identity. A study of asexual individuals found that nearly two-thirds had experienced minority stress based on their sexual or romantic orientation. Among the different dimensions of minority stress, victimization had the strongest association with suicidal thoughts, plans, and attempts. The link between minority stress and suicidality was mediated by impairment in health, meaning the stress was not just an abstract psychological burden but something that affected people’s functioning and wellbeing in concrete ways.18PubMed. Experiences of minority stress and their impact on suicidality among asexual individuals
This is a point worth sitting with. When asexual people experience depression, anxiety, or suicidal ideation at higher rates than the general population, the evidence suggests the problem is not asexuality itself but how the world responds to it. Invalidation from family, partners, friends, and healthcare providers all contribute. The “have you tried just having sex” comments, the assumptions that something must be medically wrong, the erasure from conversations about sexual orientation, these add up over time. Recognizing asexuality as a legitimate orientation is not just an abstract matter of identity politics. It has measurable effects on people’s mental and physical health.
What Animal Research Adds to the Picture
Studying sexual orientation in animals is tricky because animals cannot tell you how they identify. But some animal research is relevant to understanding the biological basis of sexual variation. In domestic sheep, about 8% of rams in a given population show a preference for mounting other rams rather than ewes.19PubMed Central. The development of male-oriented behavior in rams Separately, some rams are classified as “low-sexually performing” because they fail to mount or take a very long time to do so. Brain studies have found that these low-performing rams have measurably different neuron sizes in brain regions involved in reproductive behavior compared to both high-performing and male-oriented rams. Interestingly, the male-oriented rams and the high-performing rams were not distinguishable from each other on these neural measures.20PubMed. Low-sexually performing rams but not male-oriented rams can be discriminated by cell size in the amygdala and preoptic area: a morphometric study
This is a tentative but intriguing finding. It suggests that low sexual motivation and same-sex preference may have distinct neurological signatures, at least in sheep. The low-performing rams are not simply male-oriented rams who have not found the right partner; their brains look different in specific regions tied to mating behavior. Whether this maps onto the human distinction between asexuality and other orientations is speculative, but it does reinforce the idea that variation in the level of sexual motivation, not just its direction, has a biological basis that exists across mammalian species.
When You Should and Should Not See a Doctor
If you have never experienced much sexual attraction and you are not bothered by that, there is no medical reason to seek treatment. Asexuality does not need to be cured, and there is no pill, therapy, or hormone that will make you experience attraction you have never felt. That said, there are situations where a medical conversation is appropriate. If you previously had a typical level of sexual interest and it dropped sharply, that could signal a hormonal issue, medication side effect, or mood disorder rather than an emerging asexual identity. The same applies if your lack of desire is accompanied by significant personal distress, fatigue, or other symptoms that suggest an underlying health problem. The key question is not “do you want sex” but “has something changed, and does it bother you.” If the answer to both is no, you are not a patient with a disorder. You are a person with an orientation.