It's Christopher Castile, Who Played Mark Foster on Step By Step
It's the guy who played bespectacled uber-nerd Mark Foster on hit '90s sitcom Step By Step. Former child actor Christopher Castile (now 32 years old) retired after the show ended in 1998 and went on to become a — get this — poli-sci professor at Biola University in La Mirada, CA. That was a tough one, right?
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