Kaley Cuoco and Katey Sagal had previously worked together on the show "8 Simple Rules", in which Sagal played Cuoco's mother. When Sagal was cast to play Penny's mother on "The Big Bang Theory", Cuoco expressed her excitement on Instagram, saying "Once my tv mom, always my tv mom." The reunion allowed for more of Penny's backstory to be developed, as her mother and brother were introduced on the show. Fans responded positively to Sagal's appearance, with many expressing their enjoyment of seeing the two actors together again.