Jack McBrayer and Katey Sagal are joining The Big Bang Theory, it was announced today at a Comic-Con panel of the hit CBS/WBTV show’s writers. They will play, respectively, Penny’s brother and mother.

“We are finally going to meet more of Penny’s family,” EP Steve Molaro said. “We’re going to be meeting Penny’s mom and her brother in the first episode back. We’re super excited that Katey Sagal will be playing Penny’s mom.”

Both McBrayer and Sagal will make their debuts in the season 10 premiere. Sagal has played the mother to Kaley Cuoco before — on ABC’s 8 Simple Rules.

Penny’s brother has been spoken about a few times during the run of the series. He has worked in a meth lab and has spent time in prison.

The Big Bang Theory returns to CBS on Sept. 19.