Mia, 23, has already got a few credits to her name, including the TV series Buccaneers and Dangerous Liaisons, while Joe made his screen debut alongside his mom and sister in the 2022 anthology drama I Am Ruth.
The trio acted in the almost entirely improvised ITV drama about a mother desperately trying to reconnect with her teenage daughter, who has developed an addiction to social media.
"Luckily, they're good," she said, saying that "it felt normal" acting alongside them. "These are kids who have been testing [me] on [my] lines pretty much since they could read. They've seen me terrified beforehand. They've gone through it with me."
While none of her children have social media, Kate explained that she'd seen other moms endure the same hardships with their kids as showcased in the harrowing drama. "The number of girls I've seen go through it… My daughter's contemporaries talk to me about it."
She continued: "The other day, a parking attendant burst into tears when she saw me and said, 'I Am Ruth'. The thing about going through something traumatic with a teenager is that it is completely automatic for any parent to feel like it is your fault.
"So then this strange shame comes into play – and when the shame comes in, you shut down and you don't discuss it or share it. I wanted to tell a story that created a platform for people to just have a conversation. And that part of it has been overwhelming."
Kate shares Mia with her first husband, director Jim Threapleton, to whom she was married from 1998-2001. From 2003-2011, she was married to director Sam Mendes, with whom she welcomed Joe. Since 2012, she has been married to Edward Abel Smith, the nephew of Richard Branson, and they are the parents of 10-year-old son Bear.
Further in her interview, the Titanic star reflected on her relationship with fame and achieving it at such a young age (she became a global star at 22 with the release of Titanic).
"I felt like I had to look a certain way, or be a certain thing, and because media intrusion was so significant at that time, my life was quite unpleasant," she explained.
"Journalists would always say, 'After Titanic, you could have done anything and yet you chose to do these small things'… and I was like, 'Yeah, you bet your [expletive] life I did! Because, guess what, being famous was horrible.'
"I was grateful, of course. I was in my early twenties, and I was able to get a flat. But I didn't want to be followed literally feeding the ducks."
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