Warning! Spoilers ahead for Young Sheldon.

Young Sheldon features a sweet moment between Sheldon (Iain Armitage) and Mary (Zoe Perry), but it also accidentally creates a new The Big Bang Theory plot hole. CBS' premier comedy returns following a short hiatus with an episode that focuses on its titular character. After realizing that East Texas Tech's president lied to him about the existence of a so-called Grand Chancellor, Sheldon feels disappointed and dejected. Luckily for him, his mom was there to offer support and encouragement.

While Mary likes to claim that she loves all of her three kids equally, it's clear that Sheldon has a special place in her heart. The Cooper matriarch has always accommodated Sheldon's requests, despite his father, George's (Lance Barber) warning that coddling the child would do him harm. Mary and her son maintained their close bond years after he moved out of his childhood home in Texas and relocated to Pasadena. As seen in The Big Bang Theory, she continued to give in to almost all of Sheldon's wants and needs. Although, occasionally, she would put her foot down and keep him in line.

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Young Sheldon season 5 has successfully given every main character of the show ample focus thus far. But, while Sheldon has had a couple of heartwarming moments with his father, there haven't been many of those with his mother. This all changed in Young Sheldon season 5, episode 8 titled "The Grand Chancellor and a Den of Sin" as the pair came together for a heart-to-heart talk. After discovering Meemaw (Annie Potts) and Georgie's (Montana Jordan) gambling business, Mary starts to doubt her parenting skills, calling herself a failure. Sheldon refutes this after accidentally hearing her mumbling to herself about it. Subsequently, Sheldon shares his conflicting feelings on lying; although he likes being truthful, he feels that it doesn't really matter because everyone else is bluffing. Mary assures him that she likes that he's honest and hopes that he never changes. However, as revealed in its parent series, there was a time that Mary straight up asked Sheldon to lie for her, effectively creating a new The Big Bang Theory plot hole.

Mary sitting down, talking to Sheldon in Young Sheldon

In The Big Bang Theory season 2, episode titled "The Bad Fish Paradigm," Sheldon drunkenly told Leonard (Johnny Galecki) that he was asked by his mother to keep her smoking habits a secret. Apparently, Sheldon caught Mary having a cigarette in the car, and while "Jesus is okay with it... we can't tell dad." This particular moment hasn't been shown in Young Sheldon yet, although, without any additional information about when this happened, there's a chance that it could come to fruition in upcoming episodes.

For what it's worth, however, Young Sheldon has already established Mary's smoking tendencies. In season 3, as the family debated whether or not to let Sheldon go to college early, Mary snuck out to their backyard to have a cigarette. She was caught by the Coopers’ neighbor, Brenda (Melissa Peterman), who poked fun at her, but eventually became empathetic. Based on that, it doesn't seem like Mary's smoking habits are a regular thing; she only does it when she's extremely stressed.

Aside from the newly created plot hole, it's curious what exactly caused Mary to secretly have a cigarette in the car. Based on the previous incidents, the pattern is that her smoking follows a difficult period in her life. Following Sheldon's confession in The Big Bang Theory, the matter was never brought up again. Perhaps Young Sheldon could shed a light on it in its future episodes.

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