Big Bang Theory fans will finally get to know Penny's (Kaley Cuoco) family next season.The show has tapped Sons of Anarchy alum Katey Sagal to play Penny's mom and 30 Rock's Jack McBrayer to play her brother, executive producer Steve Molaro shared at a panel at San Diego Comic-Con on Friday.Both characters will be introduced in the Season 10 premiere on September 19.Catch up on all the latest Comic-Con news here!This will be the second time Sagal and Cuoco will be playing a mother/daughter pair. They also both starred on the ABC comedy 8 Simple Rules. Sagal has also recently appeared on Brooklyn Nine-Nine.The Big Bang Theory returns Monday, Sept. 19 at 8/7c on CBS.(Full disclosure: TVGuide.com is owned by CBS.)