Son of Patty Duke and John Astin.

Was accepted to Johns Hopkins University, but did not enroll.

Dominic Monaghan was his roommate for a while. Mackenzie later made a guest appearance on Dominic's TV show, "Lost" (2005).

Nephew of Ray Duke.

Has three other half brothers: David, Allen and Tom

Brother of actor Sean Astin.

Uncle of actress Alexandra Astin and Elizabeth Louise Astin.

Brother-in-law of producer Christine Astin.