The film-maker's latest picture, Rumor Has It, pits Jennifer Aniston as a woman who discovers her family is the basis for the CHARLES WEBB novel and subsequent movie detailing the affair between a college graduate and married woman.
And Reiner contends that research for the project revealed some truth behind the seemingly far-fetched script.
He says, "When the book came out, rumours spread through Pasadena as people speculated who the real Robinsons were.
"Well, we found out as we made the movie that Charles Webb, the author of the book, really had based his novel on people living in Pasadena in the '60s!
"Our film posits that these are the people it was based on; the tagline is 'Based on a true rumour'."