My wife has the deepest dimples I've ever seen—they show up every time she smiles, and honestly, it's one of the first things I noticed about her. When our first daughter was born, everyone expected her to have dimples too. She doesn't. Our second daughter? Dimples on both cheeks, just like Mom. So what's going on here? Are dimples actually dominant, or is that just another oversimplified genetics rule?
The textbook answer is yes, dimples are dominant. But real-world genetics is messier than that. Dimple inheritance involves multiple genes, incomplete penetrance, and some randomness. Let's break down what we actually know about how dimples are passed down—and why predictions aren't as straightforward as a simple Punnett square.
What Are Dimples, Exactly?
Dimples are small indentations that appear in the skin when you smile. They're caused by a variation in facial muscle structure—specifically, the zygomaticus major muscle, which controls smiling.
In most people, this muscle attaches normally to the cheekbone. In people with dimples, the muscle splits or has a shorter attachment point, causing the skin to pull inward when they smile. This creates the visible indentation we call a dimple.
There are two main types:
- Cheek dimples: The classic dimples on one or both cheeks
- Chin dimple (cleft chin): The indentation in the center of the chin
Both are caused by variations in muscle or bone structure, and both have genetic components—but they're controlled by different genes.
Dimples are caused by a split or variation in the zygomaticus major muscle. It's not extra tissue—it's a difference in how the muscle attaches to your face.
The Traditional Answer: Dimples Are Dominant
In classic Mendelian genetics, dimples are taught as a dominant trait. This means you only need one copy of the "dimple gene" from one parent to express dimples. If we use D for the dimple allele and d for no dimples:
- DD → Has dimples
- Dd → Has dimples (dominant allele masks recessive)
- dd → No dimples
According to this model, if one parent has dimples (Dd or DD) and the other doesn't (dd), there's at least a 50% chance the child will have dimples. If both parents have dimples, the chance goes up to 75-100% depending on whether they're DD or Dd.
Sounds simple, right? Here's the problem: real-world observations don't always match this pattern.
Why Dimple Inheritance Is More Complex
Studies have shown that dimple inheritance doesn't follow strict dominant/recessive rules. Here's what complicates it:
1. Multiple Genes Involved
Dimples aren't controlled by a single gene. Multiple genetic factors influence whether you develop dimples, how deep they are, and whether they appear on one or both cheeks. This makes inheritance patterns less predictable than simple single-gene traits.
2. Incomplete Penetrance
Even if you inherit the genetic variants for dimples, they don't always show up. This is called incomplete penetrance—you have the gene, but it's not expressed. That's why two parents with dimples can have children without them, even when genetics would predict otherwise.
3. Variable Expressivity
Dimples can be deep, shallow, unilateral (one side only), or bilateral (both sides). Siblings who both inherit dimple genes might express them differently—one with prominent dimples, another with barely visible ones.
4. Developmental Factors
Facial muscle development in utero plays a role. Even with the right genetic blueprint, how the muscle actually forms and attaches during development can vary, leading to different outcomes.
What the Research Actually Shows
Limited genetic studies on dimples exist because they're cosmetic and don't affect health. But here's what we know:
| Parent Combination | Expected Outcome (Classic Model) | Real-World Observation |
|---|---|---|
| Both parents have dimples | 75-100% of children have dimples | Most children have dimples, but some don't (incomplete penetrance) |
| One parent has dimples | 50% of children have dimples | Varies widely—could be more or less depending on genetic complexity |
| Neither parent has dimples | 0% of children have dimples | Rare, but possible if both carry hidden variants (recessive inheritance) |
Bottom line: Dimples do show dominant patterns, but not reliably enough to make accurate predictions for individual families.
Cheek Dimples vs Chin Dimples
Cheek dimples and chin dimples are separate traits controlled by different genes. You can have one without the other, or both, or neither. They don't necessarily travel together.
Chin Dimples (Cleft Chin)
Chin dimples are also traditionally taught as dominant, but like cheek dimples, real inheritance is more complex. Some research suggests chin dimples follow autosomal dominant patterns more reliably than cheek dimples, but incomplete penetrance still applies.
Interestingly, chin dimples are caused by incomplete fusion of the lower jaw bones during fetal development, not by muscle variation like cheek dimples. Despite both being called "dimples," the biological mechanism is completely different.
Can Dimples Appear Later in Life?
Usually, dimples are present from birth (or become visible as babies start smiling around 6-8 weeks). However, some people notice dimples appearing or becoming more prominent as they age, often due to:
- Facial fat loss: Less subcutaneous fat makes muscle attachments more visible
- Skin laxity: Aging skin may reveal previously hidden muscle structure
- Weight changes: Significant weight loss can make dimples more apparent
These aren't new dimples—they were always there genetically, just not visible until facial structure changed.
Can Dimples Disappear?
Some children have dimples that become less noticeable as they grow. This happens because:
- Baby fat fills in the indentation, masking the dimple
- Facial proportions change as the skull and face mature
- Muscle attachments shift slightly with growth
The genetic trait is still there, but it's less visible. In some cases, dimples reappear in adulthood when facial fat decreases or skin texture changes.
Why Predicting Dimples Is Hard
Unlike traits with well-studied single-gene patterns (like some blood types), dimples involve:
- Multiple genes with small effects
- Incomplete penetrance (genes present but not expressed)
- Variable expressivity (genes expressed differently in different people)
- Developmental randomness during facial muscle formation
This is why two siblings with the same parents can have totally different dimple patterns. It's similar to how height varies between siblings—multiple genetic and developmental factors combine in unpredictable ways.
Do Dimples Serve Any Purpose?
Nope. Dimples are a cosmetic trait with no known functional advantage or disadvantage. They don't affect facial muscle function, speech, or health. They're just a variation in anatomy that many people find attractive.
Some evolutionary psychologists speculate that dimples are considered attractive because they make faces appear more youthful or friendly, but there's no proven evolutionary benefit.
The Bottom Line
Dimples are generally considered a dominant trait, meaning you only need one copy of the gene to potentially express them. But inheritance is complicated by multiple genes, incomplete penetrance, and developmental factors. This is why predictions often don't match reality.
If you have dimples, your kids might inherit them—but it's not guaranteed. If you don't have dimples, your kids probably won't either—but surprises happen. Like many facial features, dimples are influenced by a complex mix of genetics, development, and chance.
For more on how genetic traits are passed down (and why simple dominant/recessive models don't always work), check out our guide on dominant vs recessive traits.