"He's really, really smart, and he's getting his master's at Harvard right now. He said, 'Oh God, no, I haven't acted since I was 9 or something. So I'm not into it.' "Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​,

The “Malcolm in the Middle” revival series will see Frankie Muniz, Bryan Cranston, Jane Kaczmarek, Christopher Masterson and Justin Berfield reprising their roles as the Wilkerson family - but Erik Per Sullivan will not be returning as Dewey,

A reason has been given for why original Malcolm in the Middle star Erik Per Sullivan turned down the upcoming Disney+ revival. The former child actor portrayed Dewey, the second youngest son. The role will instead be played by Caleb Ellsworth-Clark in the four-episode revival.