The couple — who share daughter Wyatt Isabelle, 6, and son Dimitri Portwood, 4 — revealed during their latest appearance on the Armchair Expert podcast that they don't believe in bathing their kids with soap every day.
The subject came up when co-hosts Dax Shepard and Monica Padman started discussing how frequent they shower. When Shepard, 46, insisted that Padman, 33, "should not be getting rid of the natural oil on your skin with a bar of soap every day" and instead only wash with water, Kunis, 37, and Kutcher, 43, agreed.
"I can't believe I am in the minority here of washing my whole body in the shower. Who taught you to not wash?" Padman asked, to which Kunis replied, "I didn't have hot water growing up as a child, so I didn't shower much anyway."
"But when I had children, I also didn't wash them every day," the Bad Moms actress continued. "I wasn't that parent that bathed my newborns — ever."
C Flanigan/FilmMagic/Getty Images Ashton Kutcher and Mila Kunis
"That's how we feel about our children," Kunis said.
Kutcher added, "Now, here's the thing: If you can see the dirt on them, clean them. Otherwise, there's no point."
Alberto E. Rodriguez/Getty Mila Kunis and Ashton Kutcher
Bathing babies too much with soap "can dry out his or her skin," according to the Mayo Clinic.
The American Academy of Dermatology Association say on their website that kids ages 6 to 11 "may not need a daily bath," but should at least wash once or twice a week.
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As for their own showering habits, Kunis and Kutcher both said on the Armchair Expert podcast that they refrain from using soap on their entire bodies every day.
"I wash my armpits and my crotch daily, and nothing else ever," Kutcher said of his soap usage. "I got a bar of Lever 2000 that delivers every time. Nothing else."
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While baths may not be a daily occurrence in their household, the pair do believe in washing their faces every day.
"I do have a tendency to throw some water on my face after a workout to get all the salts out," Kutcher admitted.
Kunis said, "I do wash my face twice a day."