The 46-year-old actress has nine-year-old twins Hazel and Phinnaeus and six-year old Henry with husband Daniel Moder, reported Contactmusic.
"They're only just discovering it. My daughter, especially, asks a lot of questions that I find it hard to answer modestly! She asked, talking about one of my best friends, 'Does Bonnie know you're famous?," Roberts said.
"I said, 'I think she knows'. 'How did she find out, did you tell her?' She's trying to solve an enigma, so she wants to know how others figured it out," she added.