Labyorteaux was born in Los Angeles and adopted by interior designer and talent agent Ronald Labyorteaux (1930–1992) and actress Frances Marshall, born Frances Newman (1927–2012). He is the younger brother of
Patrick, also adopted and also an actor, and Jane. An article in
People magazine from 1978 reported that he was born with a hole in his heart, was thought to be
autistic for the first five years of his life, and was unable to walk until the age of three or speak until the age of five. According to one report, his autism symptoms were managed through changes in his diet. Another source says the symptoms began to gradually disappear by the time he was seven, mentioning only the care of his adoptive family. ==Career==