wise beyond one's years

Adjective

 * 1) Particularly wise for one's age group; wiser than most others of one's age.
 * 2) * 1999, , "The Miserable Phantom Dog" (season 1, episode 3a):
 * Mrs. Bryerson: Um, aren't you a little young to be contacting the spirit world, dear?
 * Mona: I think you'll find I'm wise beyond my years.