Catherine O’Hara in Awe That Macaulay Culkin, 43, Is ‘Older Than I Was When I Played His Mother’ (Exclusive)

The two starred together in the 1990 classic 'Home Alone' and its 1992 sequel 'Home Alone 2: Lost In New York'

Catherine O’Hara still can't believe her Home Alone son, Macaulay Culkin, is all grown up.

“He's 43. That's older than I was when I played his mother!” the 69-year-old actress tells PEOPLE. “I think I was 32.” (Filming occurred in early 1990, the year O'Hara turned 34.)

“He's got a lovely wife to be, and two beautiful kids. And he just seems really happy, and I'm very happy for him,” O’Hara continues of Culkin, who is engaged to actress Brenda Song, 35. She and Culkin share two young sons.

O’Hara saw her costar from the 1990 Christmas classic and his family on Dec. 1 at Culkin’s Hollywood Walk of Fame ceremony, where she gave a speech.

"Home Alone was, is and always will be a beloved global sensation ... the reason families all over the world can't let a year go by without watching and loving Home Alone together is because of Macaulay Culkin,” she said.

Related: Macaulay Culkin Tears Up While Celebrating Fiancée Brenda Song During Walk of Fame Speech: 'My Champion'

“You so deserve your star on the Hollywood Walk of Fame. And thank you for including me, your fake mom who left you home alone not once but twice, to share in this happy occasion. I'm so proud of you,” she concluded, joking about Home Alone and its 1992 sequel, Home Alone 2: Lost in New York.

O’Hara says when she wrote her speech, she didn’t realize that Culkin would be next to her.

“I didn't know he'd be standing beside me when I spoke,” she says. “So it was much more personal than I knew it would be. I really wanted to honor him because he worked so hard as a child. You don't appreciate that. It's hard to appreciate that a child is really working. But he really made it look natural.”

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O’Hara says she didn’t foresee the film becoming a cultural phenomenon, but she had a wonderful time making the movie.

“I need to care about the whole thing. I don't care to do a great role in a bad project. You want to be part of something good, and that's how you go. Then the people that you're going to get to work with and the experience, the day-to-day experience. And in that case, it was lovely. All those kids that played our children were just lovely,” she says.

"[Director] Chris Columbus, lovely man. He's a family guy himself. I think he had like five kids already at the time. And [screenwriter] John Hughes. John Hughes wasn't there a lot, but wrote such a beautiful script, obviously. It's a perfect movie, isn't it?”

O’Hara is now costarring in the action-comedy Argylle with Bryce Dallas Howard, Sam Rockwell and John Cena. It's in theaters Friday, Feb. 2.

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