Dr. Jason Seaver (portrayed by Alan Thicke), a psychiatrist, works from home because his wife, Maggie (Joanna Kerns), has gone back to work as a reporter. Jason has to take care of the kids: ladies ' man Mike (Kirk Cameron), bookish honors student Carol (Tracey Gold), and rambunctious Ben (Jeremy Miller). A fourth child, Chrissy Seaver (twins Kelsey and Kirsten Dohring; Ashley Johnson), is born in October 1988. In the middle of season four (1988 -- 89), she was first played in her infant stage by an uncredited set of twin sisters. Then, by season five (1989 -- 90), she was played in her toddler stage by alternating twins Kristen and Kelsey Dohering. In seasons six and seven (1990 -- 92), Chrissy 's age was advanced to six years old. By the seventh and final season, homeless teen Luke Brower (Leonardo DiCaprio) is brought into the Seaver family to live with them until nearly the end of season seven.
who played the part of the homeless person who came to live with siblings mike carol ben and chrissy
Leonardo DiCaprio