Parents often observe their children, searching for resemblances in physical traits like hair color, eye shape, or a distinctive smile. This natural curiosity extends to features such as dimples, leading many to wonder if their own indentations will appear on their baby’s face. This highlights a common fascination with how traits are passed down.
What Are Dimples?
Dimples are small indentations that appear on the cheeks, especially when a person smiles. These facial features result from a variation in the structure of the zygomaticus major muscle, which is involved in facial expressions. In individuals without dimples, this muscle extends as a single band from the cheekbone to the corner of the mouth.
For those with dimples, the zygomaticus major muscle divides into two bundles as it approaches the mouth. One part connects at the corner of the mouth, while the other attaches below the corner and is tethered to the overlying skin. When this muscle contracts during a smile, the skin is pulled inward, creating the dimple. This muscular variation occurs during fetal development and has no negative health effects.
How Dimples Are Inherited
Dimples are considered a dominant genetic trait, meaning only one copy of the associated gene is needed for the trait to appear. This pattern of inheritance is described as autosomal dominant. If an individual inherits one dominant allele (gene variant) for dimples from either parent, they are likely to exhibit dimples.
While dimples are often familial, their inheritance pattern is more complex than a single-gene model. Some researchers classify dimples as an “irregular” dominant trait because their appearance can be unpredictable. This suggests that multiple genes can influence whether dimples form, or how prominently they appear. Despite these complexities, the tendency for dimples to be passed down through generations indicates a genetic component.
Predicting Your Baby’s Dimples
The likelihood of your baby having dimples depends on the genetic makeup of both parents, though the exact probabilities varies due to the trait’s irregular dominance. If one parent has dimples, there is a good chance their child will also have them, often over 50%. This is because dimples are a dominant trait.
If both parents have dimples, the probability of their child inheriting them increases, ranging from 50% to 100%. In cases where both parents are heterozygous (carrying one dominant and one recessive allele for dimples), there is a 75% chance their child will have dimples. Conversely, if neither parent has dimples, their child is not expected to have them based on standard inheritance patterns. However, the appearance of dimples can be influenced by factors such as facial fat, making them more noticeable in childhood and potentially fading with age.