By Keith Staskiewicz
Updated August 31, 2012 at 04:35 PM EDT
Jason Kempin/Getty Images

Sarah Polley has never been one to shy away from a difficult subject: her 2006 film Away from Her, which she wrote and directed, was a devastating portrait of Alzheimer’s, and even way back as a 12-year-old child actor, she stood up for herself against the wonderful magical corporate behemoth of Disney when she protested against the First Gulf War while promoting a film.

Her new documentary, Stories We Tell — which debuted at the Venice Film Festival this week — is perhaps her most fearless undertaking to date. In a blog post published Wednesday on the National Film Board of Canada’s website, the Take This Waltz director revealed the inspiration for the film, a family secret she had been holding onto for years: she had been conceived in an extramarital affair and the man she had believed to be her father, was not.

It’s worth reading the post in whole, if only because Polley puts it in more eloquent and personal terms than could be regurgitated by me. She discusses the difficulty she had keeping the secret — acknowledging the kindnesses afforded her by Canadian media journalists — and how the movie comes from her desire to tell the story on her own terms.

Polley will not be doing interviews for Stories We Tell while it is on the festival circuit, preferring instead to let it, and her blog post, do all the talking. After the slavering circus of the Kristen Stewart/Robert Pattinson scandal, it’s particularly heartening to see potential gossip turned into something of actual value. Not that it was easy, though. “I didn’t want to make it,” Polley wrote. “And I wanted to give up many times along the way, but I also didn’t want this story to be out there in the words of someone other than the many people who lived it. Now it will be written about in many other people’s words, and I’m finally at peace with that.”

The next stop for the documentary will be in Polley’s homeland at the Toronto Film Festival, which begins Sept. 6.