Mary Cooper is a devout Christian from Texas, Mary is Sheldon's mother. She has two other children besides Sheldon, including Sheldon's fraternal twin sister, Missy. Mary herself is not intellectual but is very wise; she appears to be an extremely good mother and is the only one who has ever been able to control Sheldon. Leonard described Mary as Sheldon's "Kryptonite". When Penny and Sheldon engaged in a fierce dispute, Penny called for Mary's help, who subsequently called and scolded Sheldon about his actions.