Born to rock, by Gordon Korman.
Leo Caraway (Young Republican, headed for Harvard, musical cretin) has known about McMurphy since fourth grade. McMurphy is his biological father, gone long before Leo was born. What he didn’t know was that McMurphy is Marion X. McMurphy, King Maggot of the legendary Punk band, Purge.
Sticking up for a classmate against a tinpot dictator of a test administrator loses Leo his full scholarship to Harvard. It is at that point that Leo realizes that not only is his absentee dad Punk Supreme, but having sold 25 million CDs back in the day, he is a very wealthy Punk Supreme indeed. Might this be a new and novel way to finance a Harvard education?