George Clooney on Most Surprising Thing About Raising Twins: 'They're Completely Different' (Exclusive)

George Clooney is opening up about life as a father of twins.

PEOPLE has an exclusive preview of a sit-down the actor did with Good Morning America's Michael Strahan that airs in full on Thursday, in which he reflected on the most surprising thing about raising 6½-year-old twins Ella and Alexander with wife Amal Clooney.

"Twins tell you a lot," George, 62, told Strahan, 52, who himself is a dad to four kids including 19-year-old twin girls Isabella and Sophia.

"When you have twins and you're raising [them] the same time, the same way, and they're completely different human beings, you realize how little say you have in who they are," continued George. "You try to give them some boundaries and you try to give them things that you believe in, but they're just different."

Added the Oscar winner, who was promoting his latest directorial effort The Boys in the Boat, "They come out with an opinion, and it's amazing to watch how different my kids' personalities are."

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George and Amal, 45, welcomed their children in June 2017.  Since their twins were born, the Clooneys have been vocal about their distinct personalities.

Alexander, according to George, is the more outgoing sibling — a fact that was proven when the boy crashed his dad's interview with GQ in 2021. And like his dad, he also has a funny side.

"Alexander, every morning, eight in the morning, bangs on my bedroom door," George shared on the WTF with Marc Maron podcast, noting that his son makes him "laugh out loud" with his morning routine. "I go, 'Who is it?' And he goes, 'It is I, Alexander Clooney.' "

Like many young boys, Alexander also loves cars — an obsession that can sometimes be dangerous.

"He goes outside and he hugs my car. 'Car!' and he hugs it," George said on The Ellen DeGeneres Show in 2019, going on to joke, "Which is bad when I'm driving. It's really not good. He gets right in the wheel well."

Unlike Alexander, George's daughter is fairly reserved, according to him. "Ella is very shy around adults," the ER alum told PEOPLE in 2020.

He gave even more insight into his daughter's personality in a 2021 interview with The Guardian, saying, "Alexander loves to laugh and Ella's very serious, always making sure everybody plays by the rules."

She's also a little fashionista, and looks a lot like her mother, George has said. "My daughter is up in my wife's closet with purses going, 'Mine!' " he noted to Ellen DeGeneres in 2019. "So I see this is going to be a fun, fun life for me."

And as serious as she may be, Ella is also a bit of a prankster. "My whole job, really, is to teach them terrible things," George joked in a 2021 interview with Hoda Kotb for the Today show. "My daughter has now picked up the mantle."

"She used to think it was really gross, all the things we did, but then she saw how many laughs Alexander got and now she's taken it up, too," he added.

Just on Monday, George told PEOPLE at the Los Angeles premiere of The Boys in the Boat that he's pulling out all the stops to encourage his twins to behave, sharing his relatable parenting trick around Christmastime.

“They're still all into the Santa thing, which is very helpful, because when my kids are acting poorly, let's say in July, I have a call from Santa,” he said. “And I go, ‘Hey Santa, how's it going?’ And he's like, ‘Everything's going good. How are the kids?’ "

"And I go, ‘Well, I don't know. Kids, how are you guys doing?’ They're like, [whining]. And then I get away with it,” the actor continued of teasing the pair.

Adding that he cast a “friend” as Santa, George noted, “I actually have a buddy whose phone comes up ‘Santa.’ "