Angelina Jolie: Kids Wonder Why We're Not Married Like Shrek & Fiona

By Tim Nudd

12/05/2011 at 10:35 AM EST

Hey, those people in the movies are getting married. Why aren't Mom and Dad?

That's the question Angelina Jolie and Brad Pitt's children have started asking, according to the actress, whose stance on marriage is the subject of intense interest outside the household as well.

"They have asked, yeah, because ... people get married in the movies," Jolie, 36, tells Nightline in an interview airing Monday. "Shrek and Fiona are married, you know?"

So, how does she respond? By explaining that you don't have to be married to be committed to a partner or your family.

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"We've explained to them that our commitment, when we decided to start a family, was the greatest commitment you could possibly have," she says. "Once you have six children, you're committed."

When the kids asked about marriage one day recently, Jolie joked about their possible motives. She says: "I asked them if it was just because they wanted to have a big cake."