The 'Pretty Woman' actress occasionally gets stopped while out in public, but for the most part, people just think she is a very convincing lookalike.
She said: "I don't attract that energy. I get more of, 'Psst, I have to tell you something. People tell me my daughter looks just like you.' Or my favourite, 'You look just like Julia Roberts!' 'Mm-hmm'. 'Are you Julia Roberts?' 'Yes'. 'No you're not.' "
And the 49-year-old actress - who has twins Phinnaeus and Hazel, 12, and son Henry, 10, with husband Daniel Moder - thinks people believe she leads a "fantastical" life with an army of staff, when she's actually happy to do chores herself.
She told Harper's Bazaar magazine: "I think people confuse the idea of having this fantastical job with somehow being a fantastical individual.
"Like, 'How could you possibly make breakfast?' Well, hunger is a good motivator.
"Of course [I go grocery shopping]. It's a thing of make-believe that I can't buy toilet paper because of course I can."
The 'Notting Hill' actress insists she's never been particularly competitive or ambitious and doesn't feel upset if she misses out on work.
She said: "In a business where people can be very competitive and ambitious, I had a strange lack of those emotions.
"When I didn't get a job, I'd think, 'Of course! I would have picked her too. I really believed it all had a purpose."
Julia is a big believer in fate, and tends to leave her decision making to her instincts.
She said: "My methodology is not to really have a methodology, and it worked. I have a very strong intuition, I've always gone with my gut on things...
"I wish I could take credit for the planning. It was a kind of higgledy-piggledy destiny thing, but it all worked out."