LOS ANGELES (CBSNEWS.COM)- The Big Bang Theory” family tree is growing even bigger!

During Wednesday’s PaleyFest panel in Los Angeles, it was announced that “Taxi” star Judd Hirsch has been tapped to play Leonard’s dad for an upcoming episode this season.

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Johnny Galecki admitted that he actually had a hand in casting Hirsch as his on-screen father after meeting at NBC’s James Burrows special.

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“I met this fellow a month or two ago and he’s a hero of mine and I knew that he was a hero ofChuck [Lorre] and Bill [Prady’s], so I just accosted him and cornered him and practically made him commit on the spot to play my father,” Galecki said, adding that he was inspired by Hirsch’s “Taxi” character, Alex Rieger, while filming “The Big Bang Theory” pilot. “I’m really excited about it. It’s going to be a lot of fun.”

Over the past nine seasons, very few details have been spilled about Leonard’s old man, however, we do know that he is an anthropologist who withheld affection from his son during Leonard’s childhood. He and Leonard’s mom, Beverly — played by “The Good Wife’s” Christine Baranski — got divorced after he cheated on her with a waitress from the Princeton cafeteria.

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