Mary Cooper, Sheldon's mother in TBBT, was initially portrayed as an overly devout Christian from Texas. Her religious beliefs made her overprotective and sometimes hypocritical. However, the spin-off prequel Young Sheldon showed a different side to Mary, where she was less stuck in her ways and more tolerable. Seasons 5 and 6 of Young Sheldon shed light on why Mary appeared bitter in TBBT. She lost her job at the church after her son got a girl pregnant, which led to her struggling with faith and feeling isolated from her community. Additionally, Mary and her husband, George, had financial difficulties and marital problems. All these factors contributed to making her more mean-spirited in TBBT.