"The weird thing was," says Moore, "once I'd met Bart and we had Cal, my career took off. I'd been doing well and things were building, but it was like my personal happiness really contributed to everything in my work life. It gives you balance, it makes it easier for you to do things." Happy and content at home, she approached acting with a renewed faith, and the more diverse the part the better. She was excellent as Amber Waves, the porn star in Boogie Nights, which rightly won her an Oscar nomination; hilarious as the wacky artist Maude in the Coen brothers' surreal comedy The Big Lebowski; heartbreakingly good as the mistress in Neil Jordan's The End of the Affair (another Oscar nomination - she's had four in total); and mesmerising in Magnolia, as a wife caring for a dying husband, where she was reunited with Paul Thomas Anderson who directed Boogie Nights.
She's regarded as the natural successor to Meryl Streep, but doesn't confine herself to the arty roles that have won her most acclaim. She certainly won't shy away from more commercial fare and her new role in the frothy Laws of Attraction is testament to that. "I'd done The Hours and Far From Heaven and I was ready for something light. You do tend to say, 'OK, I've done something big, let's do something small; I've done something funny, let's do sad.' But, obviously, you can only choose from what comes your way." These days, of course, more and more scripts come her way, but that wasn't always the case.
Moore was born Julie Anne Smith on Fort Bragg military base in Fayetteville, North Carolina, the eldest of three children. Her father was an army colonel turned military judge and her mother a Scottish-born psychiatric social worker. The family was constantly on the move - more than 20 times across America and then in Europe. "It's not the easiest thing in the world, but I wouldn't change it because it makes you who you are and gives you a good sense of who you are in the world." She worked hard at whatever school she found herself in, made friends relatively easily and was bookish and a bit of a teacher's pet. "I've always been the 'do your homework, show up on time, be prepared' type."
She was often teased over her red hair. "Kids all want to be like everybody else and not everybody has red hair. It makes you stand out. I didn't like it one bit. But now I don't really think about it. I have a little girl with dark auburn hair and a little boy with light red hair and I think it looks beautiful."
Her colouring - the hair and the milky-white skin - come from her Scottish side. Her mother, Anne, emigrated with her family to the States from Argyll in the Fifties. "My mother used to say, 'You have to remember, you children are not Americans,' which meant, of course, that my mother was out of her mind, because we are. But it was important to her to say, 'You are part of me and I'm from somewhere else.'"
Her parents first met at the local church when they were 12. "They went to the junior prom together and married when they were 19 and 20. Now they've been together for 44 years and that's kind of extraordinary. I think they've had their ups and downs, but they stuck with it and they seem very happy. Growing up they seemed such young parents. It's hard to have children when you are very, very young. For me it's been completely different, I wanted to have some perspective on life before I started having children."
Moore was at the American High School in Frankfurt when she made the decision to act. A teacher praised her performance in a production of Moli re's 17th-century comedy Tartuffe, and she plucked up the courage to tell her parents. "Was I crazy? There are thousands and thousands of people who want to do this but there are only a couple of hundred actors who work consistently in film."
After studying drama at Boston University, she changed her name (Julie Smith had already been taken, so she joined her Christian names and added her father's middle name) and moved to New York, thinking she would concentrate on theatre. Instead, she wound up on daytime TV, which could have been the death of a promising career right there at the outset.
A brief stint on The Edge of Night was followed by a three-year run on As The World Turns playing twin sisters, a dual role that won her an Emmy. She learnt how to think fast and accepted that maybe the movies would have to do without her. "A lot of actors overanalyse it and say, 'Oh, I don't want to do this part because it's not good enough,' or 'I only want to be thought of as this.' But I just wanted to work. And in a way, it really saved me because that's exactly what I did, I worked really hard. You try to work and make every experience as valuable as the last one. That's my approach and it's always been that way."
It's a clear-headed, no-nonsense attitude and it typifies Moore's outlook.
And that pragmatic view extends to a realistic appraisal of what an actor - more precisely, a Hollywood star in her forties in an industry obsessed by youth - has to bring to the table. "As actors, we all have to be aware of that kind of stuff but I don't feel ruled by it, I don't feel it's something that's making me crazy. I'm kind of grateful for it, too, because I think it makes me aware of my health in a weird sort of way. And I want my body to last as long as possible because I don't want to die."
Working out and eating well may be one thing, but cosmetic surgery is quite another. "I think the current Botox craze is frightening," she says. "It's sad that people feel they have to do stuff to their faces. I don't understand it. I think we have to get beyond that stuff, because people are holding up standards that don't seem human - it doesn't look normal and it's not beautiful. I can't see a life that's been lived in that face. I don't want to look like I did when I was 25, because it's not appropriate to where I am in my life. We all want to look the best we possibly can, but you should look like who you are and what you have going on in your life."
It would be wrong to portray Moore as an insecurity-free actress, if such a creature could ever exist. She seems to crave the challenge of a different genre, but then frets about whether she can meet the test. Laws of Attraction is a romantic comedy that hopes to pay homage to such classics as the Katharine Hepburn/Spencer Tracy films of the Forties. "I'd never done anything like this before," she says. "And everybody feels a little insecure, particularly when they try something new. I had a lot of trepidation about this movie. I still do. It's comedy and I don't usually do that and you worry that people will shout, 'You're not funny! Go back to tragedy!'"
Moore is as busy now as ever. There's another comedy and a thriller already in the can, and she'd like to do a kids' film - "with a big dog" - for her own children. "Well, there aren't many of mine they can watch at the moment." Her family life, along with the professional one, is "wonderful", so why not combine the two, she reasons? And whereas once she would fret about work, these days she's just happy where she is. "One of the things that makes me grateful about being a mother is that it gives me a place in time. I know who I am and where I am, whereas I used to be somebody just trying to build a career. Now I'm in mid-career, I have children and a marriage; that's where I am."
And for Julianne Moore, that makes it so much easier to become someone else.
Laws of Attraction opens next Friday
