Wisdom teeth, also referred to as third molars, affect each individual in different ways. This includes the amount of time it takes for them to erupt, or become visible.
Function
Wisdom teeth don't serve a particular purpose. Unlike the others, they are not necessary for chewing and swallowing. Instead, they are an extra set of molars that are often removed in order to prevent probable dental complications, including cysts and permanent tooth damage.
Time Frame
Of all the teeth, third molars are the last to come in. According to the American Association of Oral and Maxillofacial Surgeons, this generally occurs at 17 years of age, although some people experience this sooner or much later. Not long after, wisdom teeth are extracted if they do not erupt properly.
Fun Fact
Wisdom teeth are got their name because they are the last set of teeth to come in, at a time when young adults have presumably grown "wise."