A trait is something about you that makes you “you.” When your mother says that you get all your best traits from her, she means you have the same charming smile and the same brilliant mind as she has.
In science, trait refers to a characteristic that is caused by genetics. Having green eyes or being shorter than average are traits a person might have. In more general use, a trait is an important part of someone’s personality or appearance. Try to describe your favorite teacher in three words and you’ll probably come up with a list of her essential traits — such as compassionate, calm, and kooky.
Dimples are usually located on mobile tissue, and are possibly caused by variations in the structure of the facial muscle known as zygomaticus major. Specifically, the presence of a double or bifid zygomaticus major muscle may explain the formation of cheek dimples. This bifid variation of the muscle originates as a single structure from the zygomatic bone. As it travels anteriorly, it then divides with a superior bundle that inserts in the typical position above the corner of the mouth. An inferior bundle inserts below the corner of the mouth. Professor John McDonald, citing limited research, concluded that dimples have been mislabeled as genetically inherited and as a dominant trait. However, the University of Utah considers dimples an “irregular” dominant trait that is probably controlled mostly by one gene but is influenced by other genes.
Having bilateral dimples (dimples in both cheeks) is the most common form of cheek dimples. In a 2017 study of 216 people with both unilateral (one dimple) and bilateral, 120 (55.6%) had dimples in both of their cheeks. Dimples are analogous and how they form in cheeks varies from person to person. The shape of a person’s face can affect the look and form as well: leptoprosopic (long and narrow) faces have long and narrow dimples, and eryprosopic (short and broad) faces have short, circular dimples. People with a mesoprosopic face are more likely to have dimples in their cheeks than any other face shape. Dimple depth and size can also vary. Singaporean plastic surgeon Khoo Boo-Chai (1929–2012) determined that a cheek dimple occurs on the intersecting line between the corner of the mouth and the outer canthi of the eye, (nicknamed the “KBC point” in dimple surgery) but people with natural dimples do not always have their dimples on the KBC point.