Who owns a family’s stories? Do we shape our lore — the anecdotes of how our parents met, the tales of sibling betrayals and truces — as a clan, or do we agree on the outlines while parting ways on the particulars? Is it possible to be anything but subjective when it comes to the legends in our own homes? This is the endlessly complicated subject of Sarah Polley’s “Stories We Tell,” a documentary inquiry into her past that ingeniously widens in scope until director and audience stand at the edge of the abyss.
At first glance, the movie’s the latest in the nonfiction mini-genre unofficially known as How My Parents Screwed Me Up, in which an earnest filmmaker pins relatives to the wall in an effort to figure out why he/she is so miserable. But Polley immediately starts dismantling the format. A talented actress (“The Sweet Hereafter”) turned gifted director (“Away From Her,” “Take This Waltz”), she initially structures “Stories We Tell” as an attempt to discover more about her mother, Diane, a force of nature who died of cancer when Polley was 11.