One thing about the Godfather 3 that's weird is Francis is directing his daughter Sofia in some emotionally, physically intimate scenes with her cousin/lover played by Andy Garcia. Her onscreen romance is incestuous which adds another level of creepiness to the film. The only reason the onscreen romance is stopped, at Michael Corleone's request is because it doesn't 'look right'.
Mario Puzo wrote the books that eventually led to the re-write by Coppola for the screen adaption. The incest was most likely Puzo's creation, but it was obviously adapted for the screen version as well. And because it is a major storyline within the movie it wasn't done on accident.
It does shed some light on potential sexual improprieties within wealthy families.
It may not be what Q was alluding to, but it is worth consideration in regards to recent drops.