Dimple

A dimple (also known as a gelasin) is a small natural indentation in the flesh on a part of the human body, most notably in the cheek or on the chin. Cheek dimples when present, show up when a person makes a facial expression, such as smiling, whereas a chin dimple is a small line on the chin that stays on the chin without making any specific facial expressions. Dimples may appear and disappear over an extended period; a baby born with dimples in their cheeks may lose them as they grow into a child due to their diminishing baby fat. They are often associated with youth and beauty (e.g. Chinese culture believes that cheek dimples are a good luck charm) and are seen as an attractive quality in a person's face, accentuating smiles. 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.