Facial dimples are not a birth defect. They are a normal anatomical variation caused by a difference in facial muscle structure, similar to having a widow’s peak or attached earlobes. Dimples require no treatment, cause no health problems, and appear in roughly 10 to 37 percent of the population depending on ethnic background. There is, however, a different type of dimple, the sacral dimple on a newborn’s lower back, that occasionally warrants medical attention.
What Causes Facial Dimples
Cheek dimples form because of a small structural variation in one of the muscles responsible for smiling. This muscle, which runs from your cheekbone to the corner of your mouth, is normally a single band of tissue. In people with dimples, it splits into two parts. That split creates a fibrous connection that tethers the muscle to the skin of the cheek. When you smile and the muscle contracts, the tethered spot gets pulled inward, creating the visible indentation.
Chin dimples (sometimes called cleft chins) have a different cause. They result from variations in a small muscle at the base of the chin that creates subtle indentations in the overlying skin. While cheek dimples only show up during facial expressions like smiling, chin dimples are often visible all the time because they’re shaped by the underlying bone and soft tissue structure rather than by muscle movement alone.
Genetics of Dimples
Dimples are usually described as a dominant genetic trait, meaning you only need to inherit one copy of the relevant gene variant from one parent to develop them. But the genetics are murkier than most people realize. The National Library of Medicine notes that some researchers question whether dimples are truly inherited in a simple dominant pattern, and the specific gene or genes involved have never been identified. Very little formal research has been done on dimple inheritance, so the “dominant trait” explanation you may have learned in biology class is more of a working assumption than a proven fact.
This uncertainty explains why dimple inheritance doesn’t always follow predictable patterns in families. Two parents with dimples can have a child without them, and two parents without dimples can occasionally produce a child who has them.
How Common Are Dimples
Prevalence varies widely across populations. A study of Sudanese medical students found dimples in about 10.5 percent of participants, while a Nigerian study reported them in 37.2 percent. Among those who have dimples, cheek dimples are by far the most common type, accounting for about 60 percent of cases. Chin dimples make up roughly 21 percent, and shoulder dimples about 14 percent.
Interestingly, that same Sudanese study found dimples were slightly more common in males (12.7 percent) than females (8.7 percent), which runs counter to the popular assumption that dimples are more of a feminine trait. Most dimples are genetic in origin (about 62 percent in that study), though a small number result from other causes like dental development or prior medical procedures.
Sacral Dimples Are a Separate Issue
While facial dimples are purely cosmetic, sacral dimples occupy a different medical category. A sacral dimple is a small indentation in the skin at the base of a newborn’s spine, just above the buttocks. Most sacral dimples are small, shallow, and completely harmless. Pediatricians routinely check for them during newborn exams, and the vast majority need no follow-up.
A sacral dimple raises concern only when it appears alongside certain other features: a nearby tuft of hair, a skin tag, a small lump, or an area of discolored skin. These additional signs can indicate an underlying spinal issue. The location also matters. According to pediatric neurosurgery guidelines, dimples positioned more than 2.5 centimeters above the anus are considered atypical and may prompt an ultrasound to rule out spinal cord abnormalities. A simple, shallow dimple sitting right over the tailbone, even a large one, does not appear to carry a higher risk.
So when parents hear the word “dimple” in connection with possible birth defects, it’s almost always referring to sacral dimples with unusual features, not the facial dimples most people think of.
Why Dimples Get Confused With Defects
The confusion likely stems from the technical language used in medical genetics. Dimples are sometimes described as a “minor congenital anomaly,” which sounds alarming but simply means a structural variation present at birth that falls outside the most common pattern. Plenty of normal human features qualify as minor anomalies: attached earlobes, a single palmar crease, or a gap between the front teeth. These are differences in development, not defects. They don’t impair any function, don’t require treatment, and don’t signal an underlying health problem.
Facial dimples fit squarely in that category. The split muscle that creates them works just as well as a non-split one. People with dimples smile, chew, and move their faces with no functional difference whatsoever. In many cultures, dimples are considered an attractive feature, which is why dimple-creation surgery has become a popular cosmetic procedure. That’s a far cry from a birth defect.