Played by Raegan Revord
Missy (Melissa) is Sheldon's twin sister.
Missy doesn't share Sheldon's exceptional intelligence, but she's a very intuitive child.
Sometimes Missy teases Sheldon with her older brother Georgie, but mostly the twins have a special bond.
The confide in each other, Missy would be lost without Sheldon, and vice versa.