May 06, 2016 01:35 PM

Mark Ruffalo‘s son Keen is in his teens now, but he once was an adorable toddler just like everyone else — except for the fact that he has one very famous father.

PEOPLE caught up with Ruffalo, 48, at the Love Heals 2016 Gala benefiting the Alison Gertz Foundation for AIDS in New York City Tuesday night, and the Oscar-nominated actor opened up about the hilarious moment his son first caught a glimpse of his dad on television when he was around 2 or 3 years old.

“The first time he ever saw me on TV, I was away and he was there with the nanny,” Ruffalo explains. “He saw me on TV and he ran to the TV and started banging on the side of it, like: ‘How is he? Papa! Papa! Come out, come out!’ “

“It was really sweet,” Ruffalo adds with a laugh. “It was so literal for him. He literally thought I was in the TV!”

Evan Agostini/Invision/AP

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Of course, his kids are growing up — Keen is almost 15 and daughters Bella Noche and Odette are 10 and 8, respectively — and now they’re used to watching Dad’s movies, or at least the PG ones.

“Most of the movies I’ve done my kids can’t watch yet, technically,” Ruffalo says. “But yeah, the ones that they can, they have seen all of them.”

As for one movie Ruffalo would love for his kids to never see?

In the Cut,” he says, referencing the 2003 romance thriller he starred in with Meg Ryan. “It’s full-frontal nudity. And it’s like, lots of sex.”

— Aurelie Corinthios

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