Up to 2 percent of the population is born with an extra set of wisdom teeth. A person may be born with four extra teeth, reports Colgate.
Wisdom teeth generally come in during teen years, though it is unknown why humans have them. An extra set of molars may have beneficial to early human ancestors who ate tough, uncooked foods, according to The Smithsonian Institution. Through evolution the jaw has become smaller, and it lacks enough room to fit the extra teeth; therefore, extraction is needed. If there is a second set behind the original set, they too most likely need to be removed, reports Colgate.