Judd Apatow explained that working with his own kids — Maude and Iris, who star in his latest film, “This Is 40” — can be nerve-racking. “I’m afraid that they’re gonna want to leave,” he explained at a Q&A for the film moderated by David Carr. “Like, literally just go, ‘I want to go home and watch ‘Sponge- Bob!’ ” He added that putting your own family in your movie also has added pressures, saying, “You can’t make a crappy movie with your family. That’s really embarrassing.” Also on the panel was Apatow’s wife, and co-star of the film, Leslie Mann, as well as Paul Rudd. On being 40, Apatow added, “There’s this idea that you’re supposed to mature and that’s not fun.” Anyone who acts mature is probably someone who is doing something they shouldn’t behind closed doors.”