Marionette lines are creases or folds that run vertically from the corners of the mouth down to the chin. Ironically, marionette lines are not caused by years of laughing. The lines are a common result of the natural aging process that includes a combination of depleting fat (and other facial tissue underneath the skin) with a loss of skin elasticity.
Genetics can also play a key role in the development of marionette lines and how prominent they become. In fact, genetically susceptible individuals can begin to develop some degree of nasolabial folds during their childhood.