To hear Sheldon Cooper (Jim Parsons) talk about his Meemaw (June Squibb) and neighbor Penny (Kaley Cuoco), his feelings toward these two women couldn't be more different. Regarding Meemaw, the theoretical physicist speaks very highly of her, often sharing how she'd call him "Moonpie." As for Penny, he's regularly judgmental of the Cheesecake Factory waitress. Still, Sheldon trusts her to care for him when he's sick and doesn't hesitate to knock on her door when he needs advice or a place to stay.
When taking into consideration the younger version of Meemaw (Annie Potts) on "Young Sheldon," many fans feel that Sheldon unintentionally sees traits of his grandmother in Penny. This is why, despite his sarcastic commentary, he keeps her in his life, even when she's on a break from dating Leonard Hofstadter (Johnny Galecki).
On Reddit, u/bookedwebstress said, "Meemaw is beautiful, strong-willed, sarcastic, doesn't take any guff, likes to drink and almost always has a boyfriend or two in tow. Sound like someone else we know? I wonder if Sheldon felt a connection to Penny because subconsciously she reminded him of his Meemaw?"
Other viewers agree but feel that Penny also represents another member of the Cooper clan.
While Sheldon's twin sister Missy (Courtney Henggeler) isn't in many episodes of "The Big Bang Theory," she has a key role in "Young Sheldon," in which Raegan Revord portrays the character. She's tough, sassy, and stands up for herself when her brother starts to act intellectually superior.
Still, she has a massive place in her heart for Sheldon. A prime example is in the Season 2 episode "A Tummy Ache and a Whale of a Metaphor," which sees Missy deeply miss her brother — and even sleep in his bed — while he's at the hospital having his gallbladder removed. The same goes for Penny. Sheldon might drive her crazy sometimes, but she's always there for him, whether she's beating up a bully on his behalf or teaching him about common social conventions.
U/MajorZombie7204 said, "He goes to both of them [Penny and Missy] to get opinions on social interactions. The scene ... of going to get Missy on what to do about watching television with Wayne [Doc Farrow] sleeping on the couch is extremely similar to one in TBBT. There he went over to Penny to figure out what to do when there was a tie on Leonard's door. In any case, Penny is very similar to the people in his family. That made it easier for him to be comfortable with her."
U/SkatingGeek added, "Combined, Penny really filled the void for Sheldon."