Some people naturally have smile lines or dimples, while others don’t—and these differences are largely shaped by genetics, facial structure, and lifestyle. Smile lines, medically known as nasolabial folds, are creases that run from the sides of the nose to the corners of the mouth. They tend to deepen with age as the skin gradually loses elasticity. Dimples, on the other hand, are caused by variations in facial muscles and are usually inherited. They form when the zygomaticus major muscle splits, pulling the skin inward to create a small indentation when a person smiles.

Lifestyle factors can also influence how noticeable smile lines become. Sun exposure, smoking, and repeated facial expressions can all make these lines more pronounced over time. People with fuller cheeks or more defined facial features may naturally show deeper folds, even at a younger age.

Although smile lines are often associated with aging, they’re also widely viewed as signs of a joyful, expressive life. Both dimples and laugh lines reflect emotion, warmth, and human connection—visible reminders of moments filled with laughter and meaning. In many cultures, dimples are seen as symbols of beauty, charm, or even good fortune, while smile lines are often admired as marks of character and happiness.