Sheldon Cooper would have the audience believe that his dad was the lying cheater of the family, but he wasn't half as bad as his mom.
In The Big Bang Theory, adult Sheldon has repeatedly said that his father committed adultery when he was just a teen. At one point, he even admitted to Penny that at the age of 13 he had witnessed George "having relations with another woman," which is when he had taken up a habit of knocking thrice before entering a room.
Young Sheldon hasn't seen this storyline unfold exactly as Sheldon remembers it. He is already 14 years old, and the affair has yet to happen. However, George has gotten too cozy with Brenda, the Coopers' neighbor, and at one point, he had a chance to cheat on Mary, but a heart attack intervened.
Still, Mary and the rest of the audience seem to believe that George's emotional infidelity is just as bad as a potential physical one. However, we have to talk about the elephant in the room – Mary's close relationship with Pastor Rob is even worse.
Mary has given both George and Brenda a hard time, but she denies her own attraction to Pastor Rob. She loves spending time with him, she has steamy dreams about him, and she even gets jealous at one point when she sees him with another woman.
At the very least, George feels guilty about what could have been with Brenda, and he tries his best to avoid going any further with her. Mary just keeps making excuses for herself and believing them. Lying isn't a sin, but lust is, Mary!
Until the events that adult Sheldon describes in The Big Bang Theory come to pass, we all need to get off George's back. He hasn't done anything wrong just yet, and Mary needs to watch her own behavior before commenting on someone else's.
Whose side are you on?