David Hallyday (born David Michael Benjamin Smet; 14 August 1966) is a French singer, songwriter and amateur sports car racer. Hallyday was born in Boulogne-Billancourt and is the son of the French singers Johnny Hallyday and Sylvie Vartan. David Hallyday is a first cousin of actor Michael Vartan. He is the older half-brother of actress Laura Smet. Hallyday is most known for writing music for others, including a collaboration with his father on the 1999 album Sang pour sang. He appeared in the teenage comedy He's My Girl (1987), also performing its title theme song. "He's My Girl" reached #79 on the U.S. Billboard Hot 100 and #72 on Cash Box. His 1991 album Rock 'n' Heart spawned a bigger hit, "Ooh La La", which reached #51 on the Hot 100. Hallyday married Estelle Lefébure on 15 September 1989; they divorced in 2001. They have two ch...