Keaton was born in Coraopolis, Pennsylvania. He lived in Robinson Township, Allegheny County, Pennsylvania. His father, George A. Douglas, worked as a civil engineer and surveyor, and his mother, Leona Elizabeth (nee Loftus), a homemaker, came from McKees Rocks, Pennsylvania. Keaton was raised in a Catholic family. He is of Irish and Scots-Irish ancestry. He attended Montour High School in Pennsylvania. Douglas studied speech for two years at Kent State, before dropping out and moving to Pittsburgh.