John Williams has scored all seven Star Wars movies to date, but even he isn’t in on the closely guarded secret of Rey’s parentage. Nonetheless, that hasn’t stopped the Oscar-winning composer from speculating on the Force Awakens protagonist’s family tree.

According to an Indie Revolver report, Williams shared his best guess during a performance with the Boston Pops on Thursday evening.

“I never asked J.J. Abrams who Rey’s father is, but I think it’s Luke Skywalker,” Williams said. “Your guess is as good as mine, though.”

Williams’ theory is a common one — arguably the most common one — although some Star Wars fans have speculated that Rey (who is played by Daisy Ridley) is a descendant of Obi-Wan Kenobi. Theories about Rey’s mom abound as well.

While on the subject of Rey, Williams also addressed his potential involvement on Star Wars: Episode VIII, though he didn’t give a definitive answer whether he’ll return.

According to Indie Revolver, Williams said he wasn’t sure he’s up to it but also doesn’t want anyone else writing music for Rey. That, of course, would only leave one man for the job.

Star Wars: Episode VIII opens Dec. 15, 2017.