Dimples have been taught in biology classrooms for decades as a textbook example of simple dominant inheritance, but that reputation is not well supported by modern genetics. The trait does run in families, and there is clearly a genetic component, but calling dimples “dominant” oversimplifies how they actually arise. The anatomy behind a dimple involves a specific muscular variation, and emerging research on facial morphology suggests the genetics governing such traits are far more complex than a single gene with two versions.
What Actually Creates a Dimple
A cheek dimple is not a defect in skin or fat. It is an anatomical quirk of the zygomaticus major, the facial muscle that pulls the corner 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 people with dimples, the zygomaticus major is split into two bundles, a condition anatomists call a bifid or double zygomaticus major. The lower bundle of this split muscle has an attachment point partway along its length that connects directly to the underside of the skin. When the muscle contracts during a smile, it pulls the skin inward at that attachment point, creating the visible indentation we recognize as a dimple.1PubMed. Double or bifid zygomaticus major muscle: anatomy, incidence, and clinical correlation
This means a dimple is essentially a tethering effect. The skin gets tugged from underneath by a muscle that has an extra anchor point. Because the indentation depends on muscle contraction, most cheek dimples appear only during facial expressions like smiling and vanish when the face is at rest. Some people notice their dimples becoming less pronounced with age as facial fat and skin elasticity change, while others find they persist throughout life.
Where the “Simple Dominant” Idea Came From
The claim that dimples follow simple dominant inheritance became a staple of introductory genetics courses, right alongside examples like widow’s peaks, attached earlobes, and tongue rolling. The logic seemed tidy: if one parent has dimples and the other does not, and some of their children have dimples, it looked like a single dominant allele could explain the pattern. The trait appeared to show up even when only one copy of the gene was present, which is the hallmark of dominance.
The problem is that these classroom examples were chosen more for pedagogical convenience than for scientific accuracy. Geneticists have known for some time that most of the “simple Mendelian traits” taught in introductory courses do not actually follow simple Mendelian patterns. Tongue rolling, for instance, was debunked as a single-gene trait decades ago. Earlobe attachment turns out to be influenced by multiple genetic variants. Dimples fell into the same category of traits that were easy to observe, seemed to come in two clean versions (present or absent), and were therefore assumed to follow the simplest possible inheritance model. But observation of families reveals patterns that do not fit a single-gene explanation cleanly. Two parents with dimples sometimes have children without them, and two parents without dimples occasionally produce a child who has them. These outcomes are difficult to explain with strict dominance at one locus.
What Modern Facial Genetics Reveals
No one has yet identified a single “dimple gene,” and the broader picture from genomic research suggests that searching for one may be the wrong approach entirely. A large genome-wide association study that analyzed facial morphology in over eight thousand individuals of European descent found 203 genome-wide significant genetic signals associated with normal variation in facial shape.2Nature Genetics. Insights into the genetic architecture of the human face The study’s conclusion was that complex facial traits are shaped by both individual and coordinated genetic actions across many regions of the genome. If overall face shape requires hundreds of genetic inputs, it would be surprising if a single muscular variation like a bifid zygomaticus major were controlled by just one gene.
Research on twins reinforces this complexity. A study comparing identical and fraternal twins at ages twelve and seventeen found that different facial soft tissue features were governed by very different genetic architectures. Some features showed strong additive genetic influence, meaning many genes each contributing a small effect. Others showed strong dominant genetic components, meaning the interaction between alleles at individual genes mattered more. And several features, particularly lip thickness, were heavily shaped by unique environmental influences rather than genetics at all.3PubMed Central. Heritability of facial soft tissue growth in mono‐ and dizygotic twins at 12 and 17 years of age: A retrospective cohort study The pattern that emerged was that even closely related facial features can have wildly different genetic underpinnings. Some are highly heritable, others barely heritable at all. And the balance can shift as a person ages from childhood to adolescence.
Dimples specifically were not isolated in that twin study, but the findings illustrate why declaring any single facial feature “dominant” based on casual family observation is scientifically shaky. The genetics of the face are polygenic and dynamic, and the specific muscular architecture that produces a dimple likely sits within that complex web rather than floating above it as a one-gene trait.
Why Unilateral Dimples Complicate the Picture Further
If dimples were truly governed by one dominant gene, you would expect them to show up symmetrically: both cheeks or neither. A single gene produces one protein throughout the body, and bilateral structures like the zygomaticus major muscles develop from the same genetic instructions on both sides of the face. Yet a study examining dimple prevalence in an Indian population found that unilateral dimples, appearing on only one cheek, were far more common than bilateral ones. Among individuals who had dimples, roughly 73% had them on only one side, while about 27% had them on both cheeks.4PubMed Central. Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk
This asymmetry is hard to reconcile with a simple genetic switch. If a gene dictates that the zygomaticus major should be bifid, why would it affect only one side? The more plausible explanation involves developmental variation: small differences in how muscles form during embryonic development, influenced by local tissue conditions, blood supply, or signaling gradients that are not perfectly symmetrical. Genetics may set the stage by making a bifid muscle more likely, but whether it actually happens on one side, both sides, or neither may depend on developmental luck. That kind of variable expression is typical of polygenic traits and developmental processes, not single-gene dominance.
The same study also found that dimple position was not uniform. About 61% of dimples fell at the so-called KBC point, a standard anatomical landmark on the cheek, while the rest occurred at varying distances anterior to it.4PubMed Central. Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk This positional variability further argues against a simple on-off genetic mechanism. If the trait were binary, you would expect it to be consistent in its expression. Instead, dimples vary in number, location, size, and depth from person to person.
How Common Are Dimples Across Populations
Dimple prevalence varies substantially depending on the population studied. A survey across multiple ethnic groups in Pakistan found rates ranging from roughly 20% to 48%, with the highest prevalence among Saraiki-speaking participants and the lowest among Urdu-speaking participants.5World Journal of Zoology. Tongue Rolling, Folding, Cheek Dimple and Chin Cleft; Study of a Morphogenetic Traits in Quetta Population Other studies from different regions have reported prevalence figures that land at various points within a similar range, suggesting the trait is common but far from universal.
This kind of population-level variation is consistent with a trait influenced by multiple genes. Single-gene dominant traits tend to show more predictable frequency patterns governed by allele frequency in a population. Polygenic traits, by contrast, can vary widely between groups because many independent genetic variants contribute, and different populations carry different combinations of those variants due to drift, migration, and selection. The wide spread in dimple prevalence across ethnic groups fits the polygenic model better than the single-gene one.
Chin Dimples and Cheek Dimples
When people say “dimples,” they usually mean cheek dimples, but chin dimples (often called cleft chins) are a separate phenomenon with a different anatomical basis. A chin dimple results from incomplete fusion of the two halves of the jawbone during fetal development, leaving a small gap or indentation in the soft tissue covering the chin. Unlike cheek dimples, chin dimples are static: they are visible all the time, not just during smiling.
Chin clefts have also been traditionally taught as a simple dominant trait, and they suffer from the same oversimplification. Family patterns do not follow clean dominant inheritance, and the degree of clefting varies continuously from a barely perceptible crease to a deep vertical groove. This continuous variation is another hallmark of polygenic influence. For both cheek and chin dimples, the honest answer to “is it dominant?” is that the trait has a genetic basis, it tends to run in families, but calling it dominant in the strict Mendelian sense overstates what the evidence supports.
Dimples Elsewhere on the Body
Dimples are not limited to the face. Two other common types deserve mention because they sometimes come up in the same conversation and have entirely different causes.
Sacral dimples are small indentations in the skin at the base of the spine, just above the crease of the buttocks. They appear in roughly 2% to 7% of newborns and are almost always harmless. A sacral dimple that is small, shallow, and located at the midline is typically just a minor variation in how the skin formed over the lower spine. Dimples that are large, deep, far from the anus, or accompanied by unusual hair growth or skin discoloration can occasionally signal an underlying spinal abnormality, though the rate of actual pathology is low, somewhere between 0% and about 3% of screened cases.6Clinical and Experimental Pediatrics. Sacral dimple: clinical perspectives of lesions hidden beneath the skin These have nothing to do with the zygomaticus major or facial genetics.
Dimples of Venus are the paired indentations visible on the lower back, just above the buttocks, at the spots where the pelvis meets the spine. They are created by a short ligament stretching between the skin and the underlying bone and are more prominent in people with lower body fat in that region. Research has found an association between the presence of dimples of Venus and pelvic incidence, a measurement of pelvic tilt. These dimples have their own following in popular culture as an attractiveness marker, but their genetics are separate from cheek dimples.
Dimpleplasty and Surgical Creation
The popularity of dimples has given rise to a cosmetic procedure called dimpleplasty, which artificially creates the tethering effect that a bifid zygomaticus major produces naturally. The basic principle behind every technique is the same: create an adhesion between the deeper muscular tissue of the cheek and the underside of the skin, so that muscle contraction during smiling pulls the skin inward.7PubMed Central. Anatomical basis of dimple creation – A new technique: Our experience of 100 cases
Techniques have evolved since the procedure was first described in 1962, when a surgeon used a non-absorbable suture as a sling between the skin and the buccinator muscle (a deeper cheek muscle). More recent approaches involve making a small incision inside the mouth, removing a cylinder of tissue from mucosa down to the subcutaneous layer using a punch tool, and placing absorbable sutures that draw the dermis inward toward the deeper tissue.8The American Journal of Cosmetic Surgery. The Dimpleplasty: A New Streamlined Approach to Surgical Creation of Dynamic Facial Dimples, Our Experience, and Results Because the approach is trans-oral, meaning it goes through the inside of the cheek, there is no visible scar on the face.
One thing worth knowing about dimpleplasty is that the resulting dimple is typically visible at rest for the first several weeks after surgery, while natural dimples appear only when smiling. As the surgical site heals and the initial swelling subsides, the artificial dimple usually becomes dynamic, meaning it shows primarily during facial movement, more closely mimicking a natural one. Results are not always permanent; the adhesion can loosen over time, and the dimple may flatten out. The procedure is generally quick, often performed under local anesthesia, but carries the usual risks of any intraoral surgery, including infection and asymmetry if the placement is not precise.
Why Textbooks Keep Teaching It Wrong
Given the evidence against simple dominance, it is reasonable to wonder why dimples keep appearing in genetics worksheets as a dominant trait. The answer is mostly institutional inertia. Introductory biology courses need clear, relatable examples to illustrate Mendelian inheritance, and dimples check all the boxes for a teaching tool: the trait is visible, easy to score as present or absent, familiar to students, and not medically sensitive. Replacing dimples in the curriculum means finding equally intuitive examples that actually do follow simple inheritance patterns, and there are remarkably few human traits that genuinely do.
Some genetics educators have pushed back. Papers and editorials have called for retiring the use of dimples, tongue rolling, and attached earlobes as examples of simple dominance, on the grounds that they give students a fundamentally wrong picture of how human genetics works. Most human traits are influenced by multiple genes, environmental factors, and developmental variation. Teaching students that dimples are “dominant” sets up the expectation that human genetics is full of clean either-or switches, when the reality is that almost nothing works that way. The broader genomic studies of facial morphology reinforce this: over two hundred genetic signals contribute to normal variation in face shape, and no single trait can be cleanly carved out of that network and assigned to one gene.2Nature Genetics. Insights into the genetic architecture of the human face
Can You Predict Whether Your Children Will Have Dimples
This is probably the most common practical question behind the “dominant or recessive” search, and the honest answer is: not with any certainty. If both parents have dimples, their children are more likely to have them than the general population, but it is far from guaranteed. If one parent has dimples and the other does not, there is a reasonable chance some children will have them, but predicting which children and on which side of the face is beyond current knowledge.
The unpredictability comes from multiple sources. Even if the relevant genetic variants are present, developmental variation means the bifid muscle may not form, or may form on only one side. The twin study on facial soft tissue showed that the relative contributions of genetics and environment can shift between ages twelve and seventeen, meaning a feature’s heritability is not even stable across a single person’s development.3PubMed Central. Heritability of facial soft tissue growth in mono‐ and dizygotic twins at 12 and 17 years of age: A retrospective cohort study Some children are born with dimples that fade as their facial structure changes with growth, while others develop more visible dimples during adolescence as the face matures.
If you are filling out a genetics worksheet and the instructions say dimples are dominant, go ahead and use that model to complete the assignment. But if you are trying to figure out whether your future children will actually inherit your dimples, understand that the worksheet model is a simplification that does not reflect how the trait works in real families. The genetic architecture is almost certainly polygenic, the developmental process adds randomness, and the result is the kind of messy, probabilistic inheritance that characterizes most of what makes human faces look the way they do.
Dimples and Perceived Attractiveness
Across many cultures and historical periods, dimples have been considered attractive, often associated with youthfulness and approachability. This perception is widespread enough to have driven demand for dimpleplasty and inspired a range of now-debunked devices and exercises marketed to create dimples without surgery. The cultural value placed on dimples may even have contributed to their persistence in the gene pool, though proving that any specific facial feature has been sexually selected in humans is extremely difficult.
One idea that surfaces frequently is that dimples enhance facial symmetry, which is broadly linked to attractiveness. The logic sounds reasonable, but it collides with the data showing that most people with dimples have them on only one side. Unilateral dimples are, by definition, asymmetrical. If dimples were primarily valued because they signal symmetry, you would expect bilateral dimples to be seen as more attractive and unilateral ones as less so, but that distinction does not appear in how people actually perceive them. A person with a single dimple on one cheek is generally considered just as charming as someone with matching dimples. The appeal of dimples seems to be about something other than symmetry, possibly the way they accentuate the dynamics of a smile rather than the static geometry of the face at rest.