Keaton stopped by The Early Show to talk to co-anchor Hannah Storm about her latest role and the experience of making it with co-stars such as Sarah Jessica Parker.
Parker, fresh off the television series "Sex and the City," plays the prospective bride of Keaton's eldest son. She's an uptight businesswoman whose arrival for a Christmas visit turns this eccentric family upside down. "He intends to give that girl my mother's wedding ring," intones the appalled Keaton in the movie.
The ensemble comedy also stars Claire Danes, Rachel McAdams and Dermot Mulroney.
The biggest trial in this movie, Keaton says, is that this style icon had to wear a robe throughout most of her scenes.
"What a curse," she tells Storm. "All my life I dreaded getting into robes. My mother wore robes day after day after day when I was a kid. I made it my life mission to never wear a robe and then the director sticks me in a robe. I mean, can you imagine? The hell of it!"
A good script apparently offset that horror, particularly a sub-plot in which we learn that Keaton is a breast cancer survivor. In the movie, Keaton and her husband have an on-screen love scene in which the audience sees that her character has had a mastectomy.
"What I really wanted to get across was that people who live with cancer are still vital and alive and caring and frequently in love with their husbands and living a life to the full extent," Keaton says.
This is, in fact, a movie about a thoroughly modern family.
"I think it's also interesting, politically, based on the fact that one of my sons in this movie is gay and deaf and about to adopt an African-American baby," Keaton says. "I think that it also really speaks to the new definition of what family is in the 21st century here in the United States of America. Yet it's all grounded in that beautiful foundation of Christmas as this time of loving, giving, embracing your family, no matter how wacky they are."
Keaton's own family now includes two young adopted children, who spend Christmas at the beach with their mother and Keaton's mother, now 83. And, Keaton says, she couldn't play a matriarch in "The Family Stone" without thinking of her own mother.
"To me, the whole movie is about my mother, for my part," she says. "Because I really believe that finally I've got a part that forced me to sort of understand what it was like for my mother, instead of always identifying with the daughter."
Keaton, who turns 60 in January, says she "embraced maturity as late as I possibly could. I now can actually kind of identify with what it must have been like for my mother to raise four children without any help in the '50s."
Wearing a bathrobe all the while.