In the source novel, Georges de Sarre is 14 years old and Alexandre Motier is 12 years old. However, the year in which the film was made, Francis Lacombrade (1942-) was 22 years old and Didier Haudepin (1951-) was 13 years old.
The movie is based on Roger Peyrefitte's book. Peyrefitte studied in religious schools during his childhood, lived older/younger male to male love with a fan of his book, and outed many homosexual celebrities of his time, including his friend Henry de Montherlant, whose book (later a movie) La Ville Dont le Prince Est un Enfant has some coincidences with Les Amities Particulières.