Little Sheldon's grandmother is played by Laurie Metcalf. LanceBarber will play Sheldon's father. RaeganRevord and MontanaJordan will play Sheldon's twin sister and brother respectively, and ZoePerry will play Sheldon's mother, a devout evangelical Christian. Interestingly, actress LaurieMetcalf, who plays Sheldon's mother in The Big Bang Theory, is Zoe Perry's mother. Mckenna Grace plays Peggy, a talented girl and Missy's friend.