Having a single cheek dimple is not unusual at all. In fact, it is the norm among dimpled people. A study of dimple prevalence in an Indian population found that unilateral cheek dimples accounted for roughly 73 percent of all dimple cases, while bilateral dimples made up only about 27 percent. The reason comes down to a muscle variation that does not have to develop the same way on both sides of your face, and understanding that variation makes the whole picture clearer.
The Muscle Behind the Dimple
Cheek dimples are not pockets of missing tissue or dents in bone. They are caused by a structural quirk in the zygomaticus major, the facial muscle responsible for pulling the corners of your mouth upward when you smile. In most people this muscle runs as a single band from the cheekbone to the corner of the mouth. In some people, though, the muscle splits into two bundles partway through its course. The upper bundle inserts in the usual spot above the mouth corner, while the lower bundle attaches to the tissue below the mouth corner, near a point called the modiolus. Critically, that lower bundle often has a dermal attachment along its mid-portion, meaning it is physically tethered to the underside of the skin.1PubMed. Double or bifid zygomaticus major muscle: anatomy, incidence, and clinical correlation
When you smile and the muscle contracts, that tethering point pulls the skin inward, creating the visible indentation you recognize as a dimple. This means a dimple is really a dynamic feature. It shows up during facial expression and can flatten or disappear when the face is at rest, although some people’s dimples remain slightly visible even with a neutral expression, depending on how tightly the muscle grips the skin and how much subcutaneous fat sits over it.
Why Only One Side Gets the Split
Your body is not perfectly symmetrical, and muscle development is no exception. The left and right zygomaticus major muscles develop independently during fetal growth. Whether a given muscle ends up bifid (split into two bundles) or remains as a single band depends on subtle developmental variation during the weeks when facial muscles are forming. The process is not rigidly programmed to produce identical results on both sides. One cheek may end up with a split muscle and a dermal tether, while the other cheek may have a perfectly conventional single-band muscle with no skin attachment at all.
This is why having a dimple on just one cheek is so much more common than having them on both. Bilateral dimples require the same developmental quirk to happen independently on each side, which is simply less likely than it happening on just one. The analogy would be flipping a weighted coin twice and needing the same unusual outcome both times. It can happen, but the single occurrence is the more probable result. A population-level study confirms this pattern: among people with cheek dimples, unilateral cases outnumbered bilateral cases by nearly three to one.2PubMed Central. Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk
How Common Dimples Are Overall
The first meta-analysis to examine bifid zygomaticus major prevalence pooled data from seven studies and found an overall rate of about 23 percent, meaning roughly one in four or five people carry this muscle variation. But the rates varied across populations. In the American subgroup the prevalence was around 34 percent, in the Asian subgroup about 27 percent, and in the European subgroup roughly 12 percent. The differences were statistically meaningful, suggesting that genetic background plays a real role in how often this muscle variant shows up.3PubMed. Prevalence of Bifid Zygomaticus Major Muscle
Those are cadaver-dissection rates, though, which means they capture the anatomical variation even in cases where the dimple might not be visible to the naked eye during life. A person can carry a mildly bifid muscle without ever noticing a visible dimple, especially if the dermal tether is weak or if a thicker layer of cheek fat dampens the inward pull. Visible dimple rates in living populations tend to be somewhat lower, because a dimple needs both the split muscle and enough skin tethering to produce a noticeable indentation.
The Right Cheek Shows Up More Often
Among people with a single dimple, not all cheeks are created equal. In the same Indian population study, right-cheek dimples were noticeably more common than left-cheek dimples, occurring in 52 cases versus 34 on the left side.2PubMed Central. Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk Nobody has a definitive explanation for this asymmetry. One possible factor is the subtle left-right asymmetry in facial muscle development that exists in everyone, which can be influenced by everything from blood supply patterns during fetal growth to the laterality of neural crest cell migration. But the honest answer is that this right-side preference has been observed and reported without a settled mechanism behind it.
If you have a single dimple on your left cheek, you are in the minority of the minority. That does not mean anything is wrong; it just reflects the particular way your facial muscles happened to develop. Facial asymmetry is universal. Everyone’s left and right sides differ slightly in bone structure, fat distribution, and muscle architecture. A single dimple is one of the more charming expressions of that natural lopsidedness.
Where on the Cheek Dimples Tend to Land
Dimples do not appear randomly across the cheek surface. There is a predictable zone. Surgeons and anatomists use a reference point called the KBC point (named after the surgeon Kho Bhoo-Chai), which sits at the intersection of a vertical line dropped from the outer corner of the eye and a horizontal line drawn from the corner of the mouth. In the Indian population study, about 61 percent of naturally occurring dimples fell right at this point. The remaining 39 percent appeared anterior to it, roughly a centimeter closer to the nose on average.2PubMed Central. Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk
This clustering makes sense anatomically. The KBC point corresponds to where the zygomaticus major passes through the zone of maximal cheek fullness, and it is the area where a split in the muscle would most naturally create visible skin tethering. Dimples that sit further forward likely reflect cases where the bifid split occurs at a slightly different point along the muscle’s course, or where the dermal tether attaches a bit more anteriorly.
The average dimple size was about 8 to 9 millimeters vertically and about 6.5 millimeters side to side. So most cheek dimples are roughly the size of a pencil eraser, though there is plenty of individual variation.
Is It Actually Genetic
The popular claim is that dimples are a “dominant trait,” inherited in a straightforward pattern. The reality is messier. There is clearly a genetic component: dimples run in families, and the population-level differences across ethnic groups point to heritable variation in zygomaticus major anatomy. But the inheritance does not follow the clean single-gene dominant pattern that gets taught in introductory biology courses. Identical twins do not always share dimple status, and the high rate of unilateral dimples complicates any simple genetic model. If a single dominant gene were responsible, you would expect it to affect both sides equally, yet it clearly does not.
The most likely explanation is that dimple formation involves multiple genes that influence facial muscle development, combined with non-genetic developmental variation. The split in the zygomaticus major may be partly genetic and partly the result of minor random events during embryonic facial development, similar to how fingerprint patterns are influenced by genes but never identical even in identical twins. So if your parents both have dimples and you ended up with just one, or none, that is completely consistent with how this trait actually works. The textbook “dominant gene” story is an oversimplification that has never held up under scrutiny.
Can a Single Dimple Appear or Disappear Over Time
Yes, and this surprises people. Some children are born with visible dimples that fade or vanish entirely as they grow up. The mechanism is straightforward: as the face grows, the relationship between the bifid muscle and the overlying skin changes. If the cheek lengthens and the subcutaneous fat layer thickens, the tethering effect weakens relative to the bulk of tissue above it, and the dimple becomes less visible or disappears. Conversely, some people notice dimples becoming more prominent with age or weight loss, because a thinner fat layer over the cheek lets the skin tethering show through more clearly.
It is also possible for a dimple to seem to appear for the first time in adulthood. This is not the muscle suddenly splitting; it was likely bifid all along, but changes in facial fat, skin elasticity, or habitual expression patterns made the dimple visible where it was not before. Weight fluctuation is the most common trigger. People who lose significant facial fat sometimes “discover” a dimple they never knew they had.
For someone with a single dimple, this means the asymmetry could become more or less noticeable depending on life stage. A child with one obvious dimple may grow into an adult with a barely detectable one, and vice versa.
Nerve Supply and Why It Matters for Asymmetry
The zygomaticus major is controlled by the buccal and zygomatic branches of the facial nerve, and these branches do not follow an identical pattern on both sides of the face. A cadaveric study found five distinct branching patterns for the nerve supplying this muscle, with no single pattern dominating overwhelmingly. The most common arrangements each appeared in roughly a quarter to a third of specimens, and the axon counts in the main nerve branches varied substantially between individuals.4PubMed Central. Nerve to the Zygomaticus Major Muscle for Facial Reanimation Surgery: A Cadaveric Study for Branching Patterns and Axonal Count
Why does this matter for dimples? The nerve supply influences how the muscle contracts and how forcefully each bundle pulls. If the neural architecture differs between your left and right sides, even a muscle that has a similar anatomical split on both cheeks could produce a visible dimple on only one side, because the contraction dynamics differ. This is another layer of explanation for why bilateral dimples are relatively rare. It is not just the muscle anatomy that needs to match; the nerve supply and the resulting contraction behavior need to cooperate too.
Getting a Matching Dimple Surgically
If you have a single dimple and want one on the other cheek, dimpleplasty is a real and increasingly common cosmetic procedure. It is typically done under local anesthesia as an outpatient procedure. Several techniques exist, including punch excision methods and suture-based approaches. One minimally invasive technique uses a needle passed through the cheek to place a suture that ties the facial muscle directly to the dermis, mimicking the natural tethering that creates a dimple.5PubMed Central. Simple Technique for Facial Dimple The knot is deliberately tied tightly to create the indentation, and the procedure typically takes under 30 minutes.
Surgeons who perform dimpleplasty on patients with an existing unilateral dimple face a specific challenge: the new dimple needs to match the natural one. Guidelines suggest placing the surgical dimple at the same vertical level as the existing dimple, or at the site of a pre-existing faint dimple on the opposite cheek if one can be detected.6Journal of Clinical and Aesthetic Dermatology. New Landmarks for the Surgical Creation of Dimples Based on Facial Form The shape of the face also matters: rounder faces may need a different suture placement than longer faces to produce a natural-looking result.
Complications can include asymmetry (ironic, given the goal), infection, scarring, and dimples that are initially too deep but soften over time as the internal scar tissue loosens. There is also the possibility that a surgically created dimple may fade or disappear entirely after a few months if the suture loosens or the tissue does not scar in a way that maintains the tether. A narrative review of dimpleplasty techniques notes that outcomes vary across methods, and no single technique has been established as clearly superior.7PubMed Central. Dimpleplasty: A Detailed Elucidation-A Narrative Review
Chin Dimples and Other Types
Not all facial dimples share the same mechanism. Chin dimples, the vertical cleft some people have in the center of their chin, are not caused by a bifid muscle. They result from incomplete fusion of the two halves of the jawbone (the mandibular symphysis) during development, leaving a slight depression in the overlying soft tissue. Because the chin is a midline structure, chin dimples are always central. You would not get a chin dimple on only one side.
Lower back dimples, sometimes called the “dimples of Venus,” are also unrelated to the cheek dimple mechanism. These are indentations over the posterior superior iliac spine, a bony landmark of the pelvis, and they are a normal anatomical feature visible in many people depending on body composition. Sacral dimples in newborns are yet another category. These small pits near the base of the spine occur in roughly 2 to 7 percent of newborns and are usually harmless, though dimples that are large, deep, or accompanied by skin changes may warrant medical evaluation.8PubMed Central. Sacral dimple: clinical perspectives of lesions hidden beneath the skin
The takeaway is that “dimple” is a catchall term for several unrelated anatomical features. A cheek dimple on one side is a muscle variation. A chin cleft is a bone-fusion variation. Lower back dimples are skeletal landmarks. They share a word but not a cause, and having one type tells you nothing about whether you will have another.
Dimples Across Species
The bifid zygomaticus major is not unique to humans. Dissections of chimpanzee facial musculature have identified a bi-layered zygomaticus major as a consistent feature, along with other mimetic muscles that closely parallel the human set.9Journal of Anatomy. Muscles of facial expression in the chimpanzee (Pan troglodytes): descriptive, comparative and phylogenetic contexts Whether chimpanzees display anything resembling a visible cheek dimple is harder to determine, because their thicker facial skin and different fat distribution would mask the tethering effect even if the muscle anatomy were right for it. Still, the shared muscle architecture suggests the split zygomaticus major is an ancient primate variation, not something that arose recently in human evolution.
This is a useful reminder that the bifid muscle is a normal anatomical variant, not a defect. It has been present in the primate lineage for millions of years. In humans it just happens to produce a visible cosmetic feature because our relatively thin cheek skin and expressive faces make the tethering effect obvious. Your single dimple is, in evolutionary terms, a very old structural quirk rendered visible by the specifics of human facial anatomy.