Michael Keaton's Son Is 'Super Proud' of His Dad's 'Full Circle' Moment with Beetlejuice Beetlejuice (Exclusive)

Michael Keaton 's son Sean Douglas is his dad's biggest fan.

At the Los Angeles premiere of Will Ferrell 's new documentary Will & Harper on Thursday, Sept. 19, Sean, 41 — who cowrote a song with Kristen Wiig for the film — tells PEOPLE that it is "absolutely" cool to get to see his father Keaton, 73, on the big screen.

"I've always been super proud of him and to see what a wonderful, full circle place that his career is in now just always makes me super proud," Sean says. "And the success of Beetlejuice is incredible."

"And it's funny, I'm going to these things, to sets of movies with my kids who are the age that I was when I visited the original sets, so it's surreal," adds Sean, who is dad to kids River, 7, and Maggie, 5.

Keaton notably reprised his role from 1988's Beetlejuice in director Tim Burton's new sequel Beetlejuice Beetlejuice, which grew into an immediate box office hit after it released in theaters on Sept. 6. "I think that they were really well-timed and organic and really fun," Sean adds of his father reprising the title role.

Keaton shared son Sean with his late ex-wife Caroline McWilliams, whom he was married to from 1982 until 1990. McWilliams, an actress known for her roles on television series like Benson and Soap, died at 64 in 2010.

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"She was great and she's just charming in everything that she was in, and it's nice to talk about her because obviously she doesn't get as much attention as my dad's career and she was a really stellar actress and just the best person I ever knew," Sean tells PEOPLE of his mother's career and life.

Keaton himself recently joked to PEOPLE that he "could have made a lot more money" had he not slowed down his career to raise Sean and more recently spend time with his grandchildren. " I will take credit for being a good father . I will give his mom enormous credit for being a tremendous mom. Great, great, great mom," he said. "And that's why he's a good kid."

"But also, you know what it is? It's him. I think there's something in some people that's just in them," Keaton added of his son. "I mean, there's no question, parenting is not just important, it's key, right? But sometimes there's just something in certain people. So, the rest of the credit I give to him. He just is built a certain way, always was. Sweet guy, thoughtful."