'Stories We Tell' Director Sarah Polley Born After Mother's Affair

Power Lunch: Sarah Polley
Jim Ross/Getty Images

Polley ate lunch at the O&B Canteen at TIFF Bell Lightbox in Toronto, ahead of the premiere of her film "Take This Waltz."

The Canadian actress-turned-filmmaker reveals her dark secret as her latest project debuts in Venice.

TORONTO – The secret is out: actress and filmmaker Sarah Polley is the product of an affair her mother, actress Diane Polley, had in the 1970s.

In a blog post on the National Film Board of Canada website, Polley on Wednesday revealed the family secret as her latest film, Stories We Tell, debuted at the Venice Film Festival.

"My father's response to this staggering piece of news was extraordinary," Polley writes, who confessed the news to her dad in 2007 after a journalist threatened to expose a dark secret she had kept to herself.

"He has always been a man who responds to things in unusual ways, for better or for worse. He was shocked, but not angry. His chief concern, almost immediately, was that my siblings and I not put any blame on my mother for her straying outside of their marriage,” she added.

EXCLUSIVE VIDEO: Sarah Polley's 'Stories We Tell' Trailer Teases Poignant Personal Tale

Polley’s mother died when she was 11 years old, and a 2006 DNA test confirmed who her biological father was.

"I had met my biological father almost by accident, though I had long suspected based on family jokes and rumors that my mother may have had an affair that led to my conception,” Polley wrote.

The actress, who has also directed Away From Her and Take This Waltz, will screen Stories We Tell in Toronto after Venice.

Polley has for now decided to let the documentary speak for itself, and will not do media interviews until it is released theatrically.

“…I desperately want, at least while the film is on the festival circuit, to have people experience and write about the film before the story – or to experience the many stories that this story has become as opposed to just my version of it. It is, after all, why I made the film in the first place,” she wrote.