Rory Kennedy, the youngest child of Robert and Ethel Skakel Kennedy, kept it all in the family for Ethel, her upcoming HBO documentary that was recently shown at the Sundance Film Festival, which ends Sunday. More than 20 Kennedys and in-laws showed up for the screening of the film, a portrait of RFK’s famously private widow filled with archival footage and home movies. Rory, whose films include Ghosts of Abu Ghraib and Indian Point: Imagining the Unimaginable, was born after her father’s assassination in 1968. She took questions from the audience:

How did you decide to finally do a film about your family, and how did you convince your mother to participate?

I’d considered doing a documentary about my mother before, but I knew that she wasn’t comfortable with it and I wasn’t really comfortable either. But Sheila Nevins [president of documentary and family programming at HBO] kept talking to me about it and finally I said fine, I’ll ask my mother. And she said yes. I think she felt that it was important. She appreciates what she’s lived through and gone through and felt that she had something to add. And I thought if she can do it, I can do it.

What did she feel was important to say now?

She has lived through so many extraordinary historical events and was on the front lines every step of the way. Selfishly, my interest was for my children and my children’s children, and being able to help capture my mother for them, who she is and what she stood for.

There’s a remarkable moment when you ask her about your father’s death. She gets choked up, and it’s the only time in the film when she says, “Talk about something else.”

Part of how my mother has gotten through so much tragedy in life is her inner strength. Religion helped too, but she is not someone who talks about or reflects on difficult moments. So I think that moment in the film speaks volumes about who she is.

What did you discover about your family?

I didn’t know my mother used to bet on the horses in college. And I had never heard the story of my father sliding down the banister at the White House the day Jack and Jackie moved in.

You were born after your father died. Is it a stretch to say you got to know him through this film?

I’d seen a lot of the documentaries about my father, but when I went through the raw footage there was just something else that came through. My mother, too. I think they’re very genuine people, and how they lived their lives was very consistent with their public face.

The early parts of the film have the sweet, happy feel of a family’s home movies. But we, the audience, know the terrible moment of your father’s assassination is coming. Did you feel that sense of dread too?

Yes, it was hard. A lot of the documentaries I’ve done, I’ve had to watch really horrible footage over and over, but eventually you get used to it. I never had that sensation of getting used to it in making this film. It always felt raw and upsetting to me.

- Bloomberg News