Celebrity Is Sean Penn Moving to Adopt Charlize Theron's Son? The couple are "very serious," a source tells PEOPLE By Tim Nudd Published on January 23, 2015 11:05 AM Share Tweet Pin Email Photo: Jason LaVeris/FilmMagic Is Sean Penn taking a key step toward becoming family with Charlize Theron? Despite reports the actor has filed papers requesting to adopt his actress girlfriend’s 3-year-old son Jackson, PEOPLE has since learned that Penn is not currently planning to adopt the boy. Penn, 54, and Theron, 39, have been dating for over a year. “Charlize and Sean are very serious,” a source close to Theron tells PEOPLE. “Charlize says this is it. Jackson already calls Sean ‘Daddy.’ ” Theron adopted Jackson in early 2012, when he was 4 months old. Jackson is her only child. Penn has a daughter, Dylan, 23, and son, Hopper, 21, from his marriage to Robin Wright. The couple have been quiet through persistent marriage speculation over the past year, but friends have said they are a great match. “[Charlize] likes guys with more substance. She finds Sean very charming and he makes her laugh,” a source told PEOPLE last year. “She definitely has him wrapped around her finger.”