PARK CITY, Utah — Ethel Kennedy prefers coming to the Sundance Film Festival when she’s not the star of a movie.

She has been to Sundance in the past to see films by her daughter, documentary filmmaker Rory Kennedy. This time, the widow of U.S. Sen. Robert Kennedy is the focus of her daughter’s film, the Sundance premiere “Ethel.”

Ethel Kennedy said she likes it better coming to Sundance “just to see Rory’s films.”

Though initially reluctant when her daughter proposed the documentary, Ethel Kennedy opens up on screen with candid recollections about the family, including falling in love at first sight with her future husband on a ski trip to Canada.

“He was standing in front of an open fireplace,” she said in an interview alongside her daughter. “I walked in the door and turned and saw him, and I thought, ‘whoa.”’

In the film, Ethel Kennedy discusses campaigning for her husband and his brother, President John F. Kennedy, the similarities and differences between her family and the Kennedy clan, and raising 11 children after her husband’s assassination in 1968.

At the time, she was pregnant with Rory Kennedy, her youngest child, who was born six months after her father’s death.

As a widow with such a big family, Ethel Kennedy said she coped simply by going about what she needed to do in tending her children.

“After Rory was born, it was — life just happened to take care of daily living, which almost had practically nothing to do with me,” she said.

In “Ethel,” airing later this year on HBO, Rory Kennedy coaxes sweet, sad and funny anecdotes out of her mother and her siblings. The Kennedys recollect their mother’s devotion to steeping the children in world affairs, her mischievous sense of humor and her rebellious streak that led to run-ins with the law, such as the time she was charged with rustling horses after freeing some mistreated animals.

Through photos and home movies, the film offers an intimate look at the life of the Kennedys, the family relating how Robert Kennedy and his children slid down a bannister in the White House after his brother was elected and how the president once cautioned his fun-loving sister-in-law not to push his Cabinet members into the swimming pool anymore.

In front of her daughter’s camera, Ethel Kennedy is unable to discuss the grief over her husband’s death.

“When we lost Daddy …” she begins, then tears up and tells her daughter, “Talk about something else.”

Rory Kennedy, whose past Sundance documentaries include the Emmy-winning “Ghosts of Abu Ghraib,” said “Ethel” probably was her most challenging film because it was so personal.

“I know my mother and she is just terrific, and I have such admiration and respect for her. She’s such a character, too. I really think she’s one of the great untold stories, not just because of all of the events she’s lived through,” Rory Kennedy said.

“But also because she’s just such a wonderful person, and I hope that comes across in the film. She’s so funny, and she is such an inspiration to me. Our family knows my mother, our close friends know her, but to be able to share her with so many other people I think was important.”