'The Big Bang Theory' season 10 updates: Katey Sagal to play Kaley Cuoco's mom again

Katey Sagal has been cast as Penny's (Kaley Cuoco) mother in the upcoming tenth season of "The Big Bang Theory."

The Toronto Sun reports that the "Sons of Anarchy" star will be playing Penny's mother Susan in the very first episode of season 10. Viewers will also be introduced to Penny's brother Randall, who will be played by "30 Rock's" Jack McBrayer.

Sagal is no stranger to playing Cuoco's mother on TV. Back in 2002, she played Cuoco's on-screen mom in the family sitcom, "8 Simple Rules." Showrunner Steve Molaro revealed the casting at the San Diego Comic-Con, saying, "Katey has played Kaley's mum before on '8 Simple Rules,' and she told us she's always up for playing Kaley's mum."

McBrayer's character Randall is also an interesting cast choice. Back in "30 Rock," McBrayer's character was known to be a huge farm-boy hick, and Penny has often been teased in "The Big Bang Theory" for growing up in a farm as well. Maybe this season, viewers will get to see more of Penny and her farm days. It's also interesting to note that Penny once mentioned that her brother went to jail for being a meth cook. Could Randall be hiding some secrets behind that sunny disposition?

Not much is known about Penny's family in the series. The viewers have already met her father Wyatt back in the fourth season, played by Keith Carradine, but so far, only the boys' families have been getting the spotlight. There have been numerous appearances from Leonard's mom Beverly (Christine Baranski) and Sheldon's mother Mary (Laurie Metcalf), but Penny's family is more or less a mystery. Before she married Leonard, fans never even knew what her last name was.

"The Big Bang Theory" season 10 is slated to debut this September.