"She's slightly resistant to answering questions," Kennedy told reporters this summer at a news conference with her mother, who at 84 looked a little more frail than she does in the film. "And there's a reason that she hasn't done an interview in 25 years. "
And then Ethel Kennedy surprised the youngest of her 11 children by saying yes. "She was game. And I know that it's not a comfortable space for her to be in, and so I also felt, I guess, a responsibility. 'Well, if she's able and willing to do this, then I should, too,' " Rory Kennedy said.
The result: A film that covers some important - and unavoidably heartrending - parts of all our history while remaining the very personal story of one family.
And it's that personal story that turns out to be the most relatable aspect of "Ethel." Because no matter how you feel about the Kennedys, their politics or their not-so-private lives, if you grew up in a family, there are probably questions you've never gotten around to asking, memories that need passing down, stories that still need retelling.
And this is the kind of movie that might just make you want to pick up a video camera or a smartphone and start asking questions.
Luckily for Rory Kennedy, who has eight siblings still living, there were plenty of people to ask.
And stories, she said, that as the youngest, she'd never heard before.
"One of the great gifts for me [was to be] . . . able to sit down with my mother to do an interview with her over the course of five days and with all of my siblings and be able to ask them every question that I've ever wanted to ask," she said.
Indeed, it's hard to imagine how she'd have managed without them. As the oldest of seven, I particularly enjoyed the brother who at first couldn't remember how many siblings he had, but as a group, they're an eloquent lot. And they have great stories.
Ethel Kennedy, who's painted here as a bit of a rebel who first took on her husband's causes and then carried them on without him, clearly wasn't as comfortable talking about herself as she was about nearly everything else.
"Introspection! I hate it!" she proclaims at one point.
Reminded at the news conference of a family story that's in the film about the time, during the J. Edgar Hoover era, that she stuck a note in the FBI's suggestion box that said, "Get a new director," she said, "It was rude, and I apologize for that."
In response to a reporter's question about where she found her "quiet strength," she first joked that there'd been nothing quiet about her family - the Skakels - growing up.
"You know, it's embarrassing to - or uncomfortable to talk about, but I'd say faith had a lot to do with being able to get through everything, and it was always very comforting," she said. "When we lost Bobby, I would wake up in the morning and think, he's OK. He's in heaven, and he's with Jack, and a lot of my brothers and sisters, and my parents. So it made it very easy to get through the day thinking he was OK."
In the film, she's at her most voluble talking about her youth, falling in love at first sight with her husband - who then dated her sister for two years before he and Ethel got together ("that was a dark period") - and about playing the ponies as a college student.
"I wasn't a very deep thinker. Like I am now," she jokes.
Deep thinker or not, she's lived an extraordinary life. And though "Ethel" can't possibly be construed as a tell-all, much less the work of an impartial observer, it's great that someone finally got her to talk at all.
Contact Ellen Gray at email@example.com or 215-854-5950. Follow her on Twitter @elgray. Read her blog at EllenGray.tv.