Annette Bening puts in another stellar performance in new drama 20th Century Women. She tells Susan Griffin why the movie struck such a personal chord

In 20th Century Women, Annette Bening plays Dorothea, a single mum in Seventies Santa Barbara. It's a time of cultural revolution and rebellion, and Dorothea's doing her best to embrace the change that's happening - both in the wider world and at home, as her teenage son grows up.

"One moment you think she's kind of hip and cool and accessible, and at other times she's very abrupt," says the actress, 58, who considers herself "pretty open" with her own children.

"We all get on very well," adds Bening of her own brood (she has four children - Stephen, 25, Benjamin, 22, Isabel, 20 and 16-year-old Ella - with her husband of almost 25 years, Warren Beatty). "There's a lot of love, but still there's always a reaching and a curiosity and a longing to know each other better. There are things I haven't told them and I think that about my parents, they're 87 and 90. I want to go home and sit down with my mum and dad and say, 'Now, what might I like to know about you that you've never shared with me?'"

Bening believes it's "a mutual curiosity" between generations, but wonders how open any parent really wants to be with their offspring. "I think we sometimes want to protect our image of us for our children. We want to be seen in a certain way by our kids. Of course, that's hopeless anyway, because they, more than anyone, see you for who you really are."

In the film, written and directed by Mike Mills, Dorothea enlists the help of two younger women to help navigate her son's passage to adulthood. There's her lodger, the punk artist Abbie (Greta Gerwig), and the provocative teenage neighbour Julie (Elle Fanning). All the while, Dorothea grows increasingly close to her other boarder, ex-hippy handyman William (Billy Crudup).

"I think Dorothea is surprised by her feelings towards William, but she's not willing to compromise who she is to take things further - and I don't know if that's good or bad, but it's very clearly who she is," explains Bening, who describes Dorothea as "a mystery". For me she was intriguing. I usually have an instinctive reaction to how I might do something, but in this case, she was very enigmatic and I thought there were so many ways she could go."

The actress says she has "really fond memories" of 1979, the year in which the film's set. "I grew up in San Diego, which is south of Santa Barbara and even more conservative, in a military town during the Vietnam War. But I was a beach kid and worked on a boat, of all places. I loved being in Southern California. When I read the script, I related to it because of so many things," she recalls wistfully.

Asked what advice she'd offer her 21-year-old self, she pauses, before revealing she wouldn't want to. "All the lessons I've learned, I've had to learn through life experiences, which I guess is true of all of us," observes Bening. "I mean, I don't want my children to go through anything difficult. I don't want them to have any pain or to suffer, and of course that's absurd, because we all have to and it's in these circumstances, as we all know, that's where the growth is."

There has been much debate about the lack of complex and nuanced roles for women in Hollywood, but Bening feels she's been "very lucky", and therefore "can't complain". "But we don't just want 'strong' roles, because that doesn't sound very interesting. Strong women are interesting because they're also weak sometimes, and they're also silly sometimes and also delightful and sexy and horrible, and that's more of a reflection of what women are really like," she remarks. "And I think that's what most of us, men too, are longing for, those more subtle pictures of women."

The film feels fresh, not only because it's dominated by females, but because there are no explosions, special-effects or stunts. "I think there are always going to be those of us who are dying for a good story, a good narrative, with characters that somehow open the world up to us, and it's part of our job in show business to enliven and enlighten people.

"And that doesn't mean everything has to be happy, I don't mean that," comments Bening. "I just mean it's our responsibility to try to show the world in all its colours, and to maintain our own sense of wonder and curiosity about the world. Even in the midst of very dark times, there's always something to laugh at, that's for sure!"

The recipient of four Oscar nominations, for The Grifters, American Beauty, Being Julia and The Kids Are All right, many thought Bening would receive her fifth for 20th Century Women. "I have gotten plenty of recognition this year, I'm very, very grateful for that. I will take what's given to me with appreciation," she says in response. "I'm so happy, I've got so many more things I'm working on and the work really is where the joy is."

A member of the Academy Awards' Board Of Governors, Bening says the diversity in this year's nominations "is great", but notes that "the important thing is to celebrate excellence, whether or not it is commercially popular". "That's the point of the Academy, and it's trying to stay away from becoming commercialised like so many of the awards are. It's not completely succeeded, but it's trying," she adds.

As for her thoughts on America's new President, Bening grins and says: "I have so much to say about Donald Trump at this point that I hardly know where to start. One thing I can say is I think it would be wonderful if the President invited the film-makers to the White House and let them show him their movies, because we all need culture in order to open our minds," she offers.

"Film can take us all over the world. It can take us from the past and into the future and that's why it's magic. That's why I love movies, why I love going to movies, I love having my heart opened, and if there's anything that might benefit Trump, it's to have his heart opened."

  • 20th Century Women is released on Friday, February 10