Back to the Future co-writer Bob Gale has poured ice water on fan hopes for another movie in the sci-fi trilogy,
The 68-year-old told the BBC that he and director Robert Zemeckis have turned down various studio approaches over the years.
He said: “You know, you don't sell your kids into prostitution. It was the wrong thing to do. We put 'The End' at the end of part three.”
In 2018, Back to the Future topped a poll of franchises movie fans would most like to see return, beating other long-dormant series including Indiana Jones and The Hunger Games.
Gale is currently promoting a musical adaptation of the original 1985 Back to the Future movie with Olly Dobson as Marty McFly and Roger Bart as Doc Brown.
He said that all involved have stood firm on the idea that Marty and the Doc should not return to the big screen.
Gale added: "We learn from the fact that so many studios have gone back to the well on some of their franchise properties too many times, and the audiences are disappointed and say: 'Oh my God, they ruined my childhood.'
"We don't want to ruin anybody's childhood, and doing a musical was the perfect way to give the public more Back to the Future without messing up what has gone before."
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Gale and Zemeckis have stood firm for years against the idea of rebooting Back to the Future, or delivering a sequel to the original films.
Last year, Gale said that star Michael J. Fox’s Parkinson’s disease was “a hurdle that we can in no way get over”.
He added: “I can't imagine anybody wants to see a Back to the Future movie that doesn't have Michael J. Fox.
“Michael J. Fox with his Parkinson's makes it impossible for him to be the grown-up version of the Marty McFly that we saw in the movie.
“I think the public wants to remember Michael J. Fox from before he had Parkinson's and it's kind of hard.”
Zemeckis agreed, simply stating that Back to the Future 4 “can’t be done” and that the fans know this.
Christopher Lloyd — who played Doc Brown in the original trilogy — is perhaps the only member of the family to break ranks, saying last year that he’d be “happy” to do a Back to the Future sequel and that he thinks it should focus on climate change.
Back to the Future: The Musical is premiering at the Manchester Opera House ahead of a transfer to the West End and a possible move to Broadway.
The show features classic tracks from the first movie, as well as new music by original composer Alan Silvestri and lyrics by Glen Ballard.
It was originally due to premiere in 2015, but has repeatedly been pushed back due to creative differences behind the scene.