Canadian actress (“Splice”) turned director (“Away From Her”) Sarah Polley engages in a bout of navel gazing with her new documentary, “Stories We Tell.” It’s about her late mother, and she assembles her siblings and other relatives and family friends for “an interrogation,” as they recollect their memories of her in building a sometimes contradictory portrait of a woman who died when Sarah was a child.

When a sister blurts out, “Who cares about our family?”, she might be speaking for the audience. All these interviews, all these conflicting accounts, all this insistence that each speaker tell “the whole story” just so an actress can indulge herself in knowing the mother she never really knew?

But Polley is getting at something deeper, at who “owns” a story, at the impact of point of view, editing and biases. And as “Stories We Tell” get deeper into this saga, the jaw-dropping revelations aren’t just ours, they’re Sarah’s. She didn’t know this woman at all.

Her aged actor father Michael narrates from a long, writerly biography of Diane, a vivacious actress he met, married and worked with on the Canadian stage. As their family started, Michael had to give up the stage and go into insurance to support them, which seemed to frustrate both him and his wife.

Others talk of the stoic and passive Michael and “good time Charlie” who was Diane, a mismatched pair if ever there was one. And as Michael vows to tell “the whole story,” as another interviewee reminds Sarah (who pops up on camera, frequently) that “the function of art is to find the truth,” and as Sarah herself finally discovers the connecting theme of her film — “memory,” and the way we organize it to tell the stories of our lives, “Stories We Tell” transcends navel gazing and reaches something bigger and broader.

Polley uses old home movies, interviews and cleverly staged recreations of home movies that blend in seamlessly with the real thing to capture a dynamic portrait of her mom, the bubbly personality that hid a lot of personal demons.

She is blessed in having her father, often shot simply in a recording studio (she makes him do re-takes), narrating from his book “the entire story.” And with each little revelation of family history — how close Sarah, the baby of the family, came to being aborted, for instance — the tale grows more complicated, more compelling and more complete.

It goes on too long, but this is personal essay filmmaking at its best, one that passes that ultimate test of such self-involved projects. It has a story worth telling.

MPAA Rating: PG-13 for thematic elements involving sexuality, brief strong language and smoking

Cast: Michael Polley, Sarah Polley, Harry Gulkin

Credits: Written and directed by Sarah Polley. A Roadside Attractions release.

Running time: 1:48