Believe it or not, it's been 30 years since Paul Rudd first charmed audiences on screens with his earliest acting roles. The star of Marvel's "Ant-Man" trilogy had his first big break with "Clueless" in 1995, but he didn't hit his comedic stride until he paired up with frequent collaborator Judd Apatow. Throughout the aughts, the two worked together on a series of movies that were funny and frank about dating, family, and friendship, including "The 40-Year-Old Virgin," "This is 40," and "Knocked Up."

In a new retrospective for GQ, Rudd dissects his career so far, sharing behind-the-scenes details about roles including his turn as Pete in the Seth Rogen and Katherine Heigl-led comedy "Knocked Up." Although Rudd played the husband of Leslie Mann's character, making him an Apatow-like avatar since Mann is married to the writer-director in real life, the actor says the film actually pulled some details from his own marriage: Namely, an argument that Rogen's slacker dad-to-be Ben has with his more ambitious baby mama, Alison (Heigl).

"When we were working on the script, Judd and Leslie had been married and together for a long time, as had my wife and I," Rudd tells GQ, "and Judd wanted to hear things from my life and my marriage and things that we, you know, were dealing with." Rudd and his wife, writer, producer, and former publicist Julie Rudd were starting their own family right around the time that "Knocked Up" was being made, and though Apatow's name ended up on the script, he ended up pulling one plot point straight from the Rudd family's lives.

The Baby Book Fight Came From Rudd's Life

"There were certain things, like, when my wife was pregnant, I didn't read the baby books, and we got in an argument about it," the actor explained. He added, "She took it as a hostile gesture, which I totally understand in retrospect." During their argument, Rudd offered a retort that ended up making it into the movie nearly word-for-word. "I said, 'What did the cavemen do without 'What To Expect When You're Expecting?''" Rudd tells GQ. In the film, much of the plot's tension comes from Ben's unwillingness to shape up and put work into his relationship to Alison and their future child. At one point, when she yells at him for not reading baby books, he jokes that Heidi Murkoff's famous pregnancy guidebook must've been carved into the pyramid walls by ancient Egyptians.

"You know, it was funny, and then it's in the movie now as Seth's character," Rudd says. The actor would go on to collaborate with Apatow several more times, and calls their projects together "some of the most fulfilling creative experiences because of the collaboration and because of the freedom that everybody feels [to try new things]." Apatow's films famously include some great unscripted moments, but Rudd also may just have a knack for good, story-shaping ideas: earlier this week Marvel Studios President Kevin Feige said that it was Rudd who first came up with the idea for Ant-Man to explore the quantum realm.

The Rudd family baby book argument is surely far in the rearview now, but the actor still remembers his wife's moment of recognition when she first watched "Knocked Up." He tells GQ, "When my wife and I saw the movie, she's like, 'Oh, so, this is an interesting documentary we're watching right now.'"

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