Named for his mother, singer/model Nico, whose birth name was Christa Päffgen. "Boulogne" is his paternal step-grandfather's surname, which he has never used professionally.
In 2001 he wrote a book about his relationship with his mother called "L'Amour N'Oublie Jamais" (Love Never Forgets).
One son, Charles b. 1999 and one daughter, Blanche b. 2006.
Appeared briefly on stage at the end of a Nico Tribute Concert at the Volksbühne, Berlin, on 17 October 2008.