What can cause geographic tongue?

Normal: It's also called migratory glossitis. It has a slight female predilection. There are two types of structures on the tongue. Filliform and fungiform papillae. The former tend to wear away faster than the later. There is no worry about 1-2% of the population have it. Not a contagious condition and no treatment is necessary. That's the quick answer. Don't worry about it as there is no treatment.