Sundance: Anderson Cooper Shares Off-Color Story About Mom Gloria Vanderbilt at Documentary Premiere

Nothing Left Unsaid: Gloria Vanderbilt  and Anderson Cooper - H 2016
Courtesy of Sundance Institute

"A lot of people know the name 'Gloria Vanderbilt,' but they don't know what she has been through."

How close are Anderson Cooper and his mother Gloria Vanderbilt?

The CNN anchor offered an off-color anecdote to explain the nature of his relationship with the 91-year-old heiress turned fashion designer and artist after the Saturday premiere of the Sundance Film Festival documentary about their lives, Nothing Left Unsaid: Gloria Vanderbilt and Anderson Cooper.

In relating how open and honest Vanderbilt is about her extraordinary love life, including her four marriages and relationships with Frank Sinatra and Errol Flynn, Cooper said his mother is not currently "hooking up" but "when she was about 85, she told me a story about someone she was dating who was the 'ninjutsu of cunnilingus,'" Cooper told the Marc Theater crowd, which included his CNN boss Jeff Zucker.

Cooper also told the story of Vanderbilt once flying to Los Angeles for a one-night "date" with Marlon Brando that was set up by Walter Matthau's future wife.

Despite the levity at the screening, the film, an HBO production directed by Liz Garbus, is a decidedly somber exploration of the grief that Vanderbilt and Cooper have endured despite being part of the family of storied American industrialist Cornelius Vanderbilt.

Through interviews with her son, as well as family archives and explanations of her art and poetry, Vanderbilt tells the story of the 1934 custody battle when she was 9 between her mother and aunt that was labeled the "trial of the century" in the New York media; her marriage at age 17 to an abusive Hollywood agent; her three divorces; the death of Cooper's father Wyatt Cooper; and, most traumatically for both Vanderbilt and Cooper, the suicide of her 23-year-old son Carter, which Vanderbilt witnessed as he jumped from the 14th floor of their New York apartment.

"A lot of people know the name 'Gloria Vanderbilt,' but they don't know what she has been through," Cooper said before the screening.

Vanderbilt did not attend because her doctors advised her not to travel to the high altitude of Park City, Utah (the snowstorm in New York didn't help), according to Cooper.

To make Nothing Left Unsaid, which Cooper first pitched to HBO Documentary Films president Sheila Nevins before getting his mom on board to participate, the family offered full cooperation, including the use of extensive family archives (Cooper is an executive producer on the film.)

"We handed everything over to Liz," he said, "92 years of [family materials] from before [Vanderbilt] was even born. I learned things about my mom that I didn't know."

Garbus, speaking after the doc screened, echoed Cooper's sentiments about Vanderbilt.

"She is a model of resilience," said the filmmaker. "She's tough and vulnerable. Most of all, she's a survivor."