After nearly a decade of vague stories about her family, fans of "Big Bang Theory" will finally get to see the mother and brother of Penny in the season 10 premiere.

A sneak peek for the upcoming season shows Kaley Cuoco's reunion with Katey Sagal, who will once again play the role of her mother. The two actresses co-starred in "8 Simple Rules," where they played the role of mom and daughter for more than 75 episodes in the comedy.

The new season will also see the debut of "30 Rock" star Jack McBrayer as Randall, the brother of Penny who is portrayed as a drug-making criminal.

According to reports, the premiere episode of season 10 will bring together everyone's families to celebrate the wedding of Penny and Leonard. There's a chance that fans will also finally get to know the surname of Penny when the series returns.

In the sneak peek for the premiere episode, Penny and her dad are sharing a beer and talking about her success as a pharmaceutical sales representative. On the other hand, Susan chastises Randall for failing to live up to his potential.

The clip shows Randall talking back to her mother, saying, "Hey! She just sells drugs, I had to make 'em!"

At the Comic-Con back in July, McBrayer made a surprise appearance at the "Big Bang Theory" panel and quipped that unlike Randall, he's only been to jail "recreationally." He also joked that he looks "real good in orange."

"Big Bang Theory" season 10 premieres on September 19, 8:00 P.M. on CBS.