One of The Big Bang Theory’s Biggest Mysteries Changes a Major Event in the Series

Penny is always the odd one out in The Big Bang Theory. At the start of the series, she’s the only woman in a friend group full of scientists who wear their passion for pop culture on their sleeves. After a couple of years, a couple of the guys get girlfriends, and while they become fast friends with Penny, they’re scientists as well, leaving her fighting to find common ground. Things wouldn’t be so bad if Penny had a good relationship back home with her family in Nebraska, but she doesn’t, with her dad admitting frequently that he wishes she had been born a boy.

One relative that Penny does speak highly of is her sister Lisa, who never appears in the flesh in The Big Bang Theory. Lisa doesn’t even show up at Leonard and Penny’s wedding in Season 10, leading to one of the biggest mysteries in the show’s history.

Penny’s Family Doesn’t Do Right By Her in The Big Bang Theory

The first hint that Penny has a complicated relationship comes in Season 2 when Leonard’s mother, Beverly, comes to Pasadena, California. Leonard warns his neighbor that his mother is a lot to handle, but Penny can’t avoid her and starts to spill all her darkest secrets. She mentions that her dad, Wyatt, calls her “slugger” and buys her masculine sports equipment to prove his displeasure with her being a girl, and her mom, Susan, doesn’t do anything to stop it. Around the same time, Penny accompanies the guys to buy a comic book for her nephew, who is seemingly Lisa’s son, which means she’s on good terms with that side of the family at least.

Penny is able to forget about her family for a while after that, as she doesn’t see her dad until Season 3 when he comes to town. She pretends to be in a relationship with Leonard because her dad likes him, but the fake couple can’t keep the ruse going. The truth coming out allows Penny to grow closer to her dad, and by the time she and Leonard tie the knot, he’s supportive of her. He even plans to head out to California when the official ceremony happens and bring the whole family.

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An Important Face Is Missing From the Crowd at Leonard and Penny’s Wedding

When Leonard and Penny celebrate their love in Season 10, everyone who’s important to them shows up. Despite hating each other, Leonard’s parents are at the event, and Sheldon’s mom, Mary, also shows up to support her son’s good friends. However, the most surprising guest is Penny’s brother, Randall, who has his fair share of issues. Throughout The Big Bang Theory, Penny drops nuggets about Randall, such as the fact that he works at a meth lab and finds himself in trouble with the law on a couple of occasions. Somehow, he gets approval to leave Nebraska and visit his sister for her wedding, which is great until it becomes clear that no one wants to talk about Lisa.

It’s possible that Lisa isn’t speaking to the rest of her family at the time of the wedding, and Penny also mentions run-ins with police that could be the cause of her absence. But The Big Bang Theory covers both scenarios with Leonard’s parents and Randall, respectively, meaning there has to be another explanation for her not showing up. The most logical one is that the writers thought it was a better idea to focus on Randall, who became an infamous figure due to his exploits, rather than Lisa, who seemed to be pretty stable in her life. That might be giving the creatives behind the show too much credit, though, because they had a habit of dropping characters when they no longer served a purpose.

Lisa never showing up didn’t take away from The Big Bang Theory‘s story. After all, the true focus of the show is found family. However, Penny has it bad enough with a brother who’s a troublemaker and a dad who never seems to say the right thing, so ignoring her sister seems like a major misstep.

The Big Bang Theory is streaming on HBO Max.

Did you remember that Penny has a sister in The Big Bang Theory? Why do you think she failed to show up at Penny’s wedding? Let us know in the comments below!