Why Nicole Richie Refuses to Judge Other Moms: 'There's No One Right Way to Be a Mother'

"The biggest lesson I learned [in being a parent] is to not judge and to be open and honest with other women," the actress and designer says

Nicole Richie is raising some seriously independent kids — at the very least, when it comes to what they wear.

The House of Harlow 1960 designer, 34, tells PEOPLE that son Sparrow, 6½, and 8½-year-old daughter Harlow have very different approaches to their fashion choices.

“They dress themselves,” says Richie, who shares parenting duties with her husband, Good Charlotte member Joel Madden, 37. “Sparrow does his own thing. He likes to wear all black like his dad.”

It turns out Harlow is a bit more flexible than her brother when it comes to what she wears.

“She has her own style,” the mom of two adds. “She likes to experiment with different looks. I am totally fine with that. What she looks like is ultimately up to her.”

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Richie and her children are spending their summer accompanying Madden and his twin brother Benji on the road for the 2016 Vans Warped Tour.

“Oh my God, they make me laugh every day,” Richie shares of her kids. “I’m always finding funny pictures and videos on my phone of them that they take.”

Unfortunately, though, it seems like the noise that comes with a tour bus might not be something Harlow and Sparrow are immune to during the night.

“I was very quiet around my kids when they were babies and now they’re light sleepers,” Richie admits. “I wish I had been a little more rough with them.”

Joel Madden Instagram

The author and former reality star is also aware that there is no one way to parent, and in her experiences she has learned to be nothing but supportive of her fellow moms’ techniques.

“I had two friends that were moms before me — I had kids very young,” explains Richie. “It was really so refreshing to see two women that have such different taste and parenting styles maintain a friendship and not judge each other for the way that they bring up their kids.”

She continues, “That’s something that’s always stuck with me because there’s not one way to raise children. There’s no one right way to be a mother. It depends on your house and lifestyle. The biggest lesson I’ve learned is not to judge!”

For more from Nicole Richie, pick up the latest issue of PEOPLE, on newsstands Friday.

— Jen Juneau with reporting by Sharon Clott Kanter