Rob Lowe's brother Chad has been cast as his sibling on 9-1-1: Lone Star

'9-1-1: Lone Star' Casts Rob Lowe's Real Brother Chad to Play His Sibling on the Show

9-1-1: Lone Star Casts a Familiar Face to Play Rob Lowe's Brother

Rob Lowe shares some laughs while hiking with his son in Palm Springs