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Rules That Everyone Follows In The Big Bang Theory Universe

From 2007 to 2019, "The Big Bang Theory" dominated the TV comedy space. Fans loved following the antics of Sheldon (Jim Parsons), Leonard (Johnny Galecki), Penny (Kaley Cuoco), Howard (Simon Helberg), Amy (Mayim Bialik), Bernadette (Melissa Rauch), and Raj (Kunal Nayyar) as they navigated the perils of adulthood and looked for love while managing to hold on to their nerdy interests. Over the course of 12 seasons, the characters evolve, get married, and move on to the next stage of their lives. Even so, certain things stay the same.

As viewers watched season after season, many noticed that key tropes and plotlines kept repeating, creating a set of rules everyone seems to follow in this fictional universe. More than just a series of recurring gags, these rules eventually determined how happy or successful certain characters were allowed to become. From invisible mothers and repeating relationships to unchanging job patterns, here are the rules everyone follows in the "Big Bang Theory" universe.

Everyone's IQ is lower than Sheldon's

The story of "The Big Bang Theory" is primarily about genius scientists trying to improve their social skills. The pilot episode sees Penny comparing her neighbors Leonard Hofstadter and Sheldon Cooper to Nobel Prize-winning mathematician John Nash. Later, viewers meet astrophysicist Raj Koothrappali, engineer Howard Wolowitz, microbiologist Bernadette Rostenkowski, and neuroscientist Amy Farrah Fowler, who are all experts in their fields.

However, Sheldon's IQ regularly outstrips his peers by a wide margin. In Season 1, Sheldon states he has an IQ of 187 compared to Leonard's 173. We later see him attending college at the age of 11 in "Young Sheldon" and watch him win a Nobel Prize of his own in the series finale of "The Big Bang Theory." In the Season 9 episode "The Positive Negative Reaction," an inebriated Sheldon is still able to offer genius-level insights, prompting Raj to admit, "Even drunk, he's still smarter than all of us."

Of course, just because Sheldon is book smart doesn't mean he has good street smarts or emotional intelligence. He regularly has trouble interpreting emotional cues and recognizing sarcasm. In the Season 3 episode "The Excelsior Acquisition," he foolishly insults a traffic court judge and gets thrown in jail, showing that even a genius-level IQ doesn't mean you know everything.

Nerds need to fall in love with every girl who shows an interest in them

Leonard immediately falls for Penny in the pilot episode of "The Big Bang Theory" and spends most of the series pursuing her — but he's not the only one. Howard also flirts shamelessly with Penny and tries to pick up every attractive woman he meets in a desperate attempt to find love. He even nearly goes broke trying to date Penny's friend Christy (Brooke D'Orsay) in the Season 1 episode "The Dumpling Paradox" when he learns she'll only stay with him if he keeps buying her presents.

Raj also goes love crazy as the series progresses. In Season 7, he dates Emily Sweeney (Laura Spencer), a dermatologist who offers him a chance at a stable relationship. However, when a bartender named Claire (Alessandra Torresani) shows an interest in him in Season 9, Raj becomes infatuated with her and breaks up with Emily, only to later screw up his relationship with Claire as well.

About the only character who seems immune to this effect is Sheldon, who's entirely uninterested in and even unaware of romantic love during the early part of the series. Ironically, several women find his behavior charming, causing them to be attracted to him. Eventually, however, even Sheldon begins finding women appealing when he meets, dates, and later marries Amy Farrah Fowler.

Nerds must be socially awkward

While "The Big Bang Theory" gives a lot of positive representation to "nerd" culture, it also reinforces a lot of unfair stereotypes surrounding nerds, particularly their supposed discomfort in social situations. Leonard bends over backward whenever Penny asks him to do anything. Sheldon dislikes associating with people outside of his small circle of friends. Howard overcompensates in his attempts to flirt with women, making them see him as creepy. And Raj is so terrified by the idea of talking to a woman that he initially becomes mute in their presence unless he gets drunk.

Eventually, the characters do become more sophisticated in their interactions with others. Leonard and Penny learn to communicate with each other better. Sheldon gains more emotional intelligence after dating Amy. Howard marries Bernadette and reveals his old "lady killer" persona came from a desire to have kids and be a good father. And Raj gets over his selective mutism and begins dating. Yet despite this, none of the "nerd" characters ever completely shake off their socially awkward personas, perpetuating the idea that all nerds have underdeveloped social skills. 

Raj can never find lasting love

The "Big Bang Theory" writers regularly found ways to put Raj's dating life through the wringer. Early seasons show he can be charming around women, but only when he's drinking alcohol or thinks he's drunk. The Season 1 episode "The Porkchop Intermediacy" shows that Sheldon's attractive twin sister Missy (Courtney Henggeler) is attracted to Raj, and he successfully flirts with actress Summer Glau in Season 2's "The Terminator Decoupling." Inevitably, however, the alcohol wears off, and Raj goes back to being a socially awkward man who can't even form words around women.

By Season 6, Raj's awkwardness begins to fade, and he dates multiple women. This seems to change the established status quo, to the point where his friends regard his relationship status as bigger news than Penny and Leonard's engagement in Season 7's "The Status Quo Combustion."

Unfortunately, all of Raj's relationships fail because he pushes his partners too far and becomes obsessed with finding the perfect woman. He even asks his family to arrange a marriage for him in Season 12 and becomes engaged to a woman named Anu (Rati Gupta). They get along, but eventually, their engagement falls apart, and Raj has to settle for going on a platonic date with "Buffy the Vampire Slayer" star Sarah Michelle Geller in the series finale. Granted, not everyone finds love, but the show really goes out of its way to sabotage Raj's relationships.

Sheldon always gets away with his bad behavior

Throughout the series, Sheldon routinely mistreats his friends. He makes Leonard wait on him hand and foot, gets Penny and Amy to drive him everywhere, and forbids anyone from sitting in "his spot" on the couch. For the most part, his bad behavior is played for laughs, but it's clear that his friends are regularly annoyed and infuriated by his selfish actions.

And yet, everyone chooses to put up with Sheldon and submit to his demands on a regular basis. Leonard shows a great deal of patience with Sheldon — most likely because he's spent his life being controlled by his similarly overbearing mother Beverly Hofstadter (Christine Baranski). Other characters aren't always as tolerant, yet everyone seems to recognize that Sheldon doesn't know when he's being mean because of the way his brain is wired. Although people do call Sheldon out for being self-centered, they generally forgive him for his poor behavior.

At the end of "The Big Bang Theory," Sheldon thanks his friends during his Nobel Prize acceptance speech and acknowledges that he hasn't always shown them how much he loves them. While it's unlikely that he'll change all of his selfish tendencies, it's pretty clear at this point that his friends have grown to accept him for who he is.

Howard can never get a doctorate

Unlike his three best friends who all earned PhDs, Howard has a master's degree in engineering from MIT. Howard is justifiably proud of his degree, stating that he can build the machines that doctors like Leonard and Sheldon can only conceptualize. He demonstrates this by designing a mechanical arm that can serve food and give massages in the Season 4 episode "The Robotic Manipulation" and even gets to go into space in Season 6 to conduct some work on the International Space Station.

However, Howard's friends — particularly Sheldon — regularly ridicule Howard for not having a doctorate like the other characters. Although Howard claims he doesn't need a doctorate, the teasing does get to him, particularly when his wife Bernadette gets her own doctorate and begins working at a significantly higher-paying job than his.

In the Season 8 episode "The Junior Professor Solution," Howard decides to finally work toward a doctorate of his own. Unfortunately for him, he starts by taking a graduate class taught by Sheldon, who ends up being so obnoxious that Howard soon quits. The series ultimately ends without Howard becoming "Doctor Wolowitz," although Sheldon does recognize that he is an astronaut in the series finale.

Penny can get other people to pay her way

Although most of the main characters in "The Big Bang Theory" have well-paying jobs as physicists or engineers, Penny starts the show as a struggling actor who's constantly broke. Many episodes see her driving a broken-down car and struggling to make her rent payments or afford a meal.

As a result, Penny starts hanging out a lot in Sheldon and Leonard's apartment and takes advantage of their friendship by eating their food and using their Wi-Fi. She routinely avoids chipping in when the others help pay the food bill and sometimes doesn't even bother to carry money in her wallet. When Leonard asks how she can walk around with no money in the Season 4 episode "The Cruciferous Vegetable Amplification," Penny simply tells him, "I'm cute, I get by."

Even Sheldon lends Penny a generous amount of money to help her pay rent in the Season 2 episode "The Financial Permeability," although Penny starts feeling guilty about mooching off so many people. Near the series' end, Penny becomes a highly paid pharmaceutical rep and begins being able to make expensive purchases, although it's clear that she can still get other people to pay for her.

Everyone breaks up and makes up repeatedly

Penny and Leonard's will-they-or-won't-they dynamic provides much of the romantic tension in the early part of "The Big Bang Theory." Fans were curious when they started a relationship during Season 3, only to watch them break up in "The Wheaton Recurrence" and then get back together in the Season 3 finale. This pattern continues throughout the series until they elope at the beginning of Season 9 and then renew their wedding vows in Season 10's "The Conjugal Conjecture."

Of course, Penny and Leonard aren't the only couple to fall into this pattern. Howard and Bernadette also break up in Season 4's "The Hot Troll Deviation" after she catches him having cyber sex with a "World of Warcraft" troll, only to reconcile and marry. Sheldon and Amy also break up, make up, and go through various rough patches, usually because of Sheldon's bad behavior.

Even Raj (whose relationships never seem to last very long) gets to follow this rule when he briefly reconciles with his old girlfriend Emily in Season 9's "The Application Deterioration" — just as he starts to date another girl. Relationships do have their ups and downs, but it often feels like the characters are riding multiple roller coasters simultaneously in the show.

Nerds need to stay nerds

In the Season 1 episode "The Nerdvana Annihilation," Penny ridicules her neighbors for their "stupid toys and costumes" and calls them pathetic for their nerdy interests. Ashamed, Leonard tries to get rid of all his collectibles, believing this will make him appear more mature. However, Sheldon points out that Penny has plenty of toys and collectibles that she loves, making her apologize for trying to turn Leonard into something he's not.

From then on, the characters grow and mature but never abandon their quirky interests. This is true of Sheldon's obsessions with trains, Leonard's science fiction memorabilia, and the gang's love of gaming. Although they sometimes need to put up with weird looks from others, the fact that they have friends with shared interests helps them keep their passions alive.

More importantly, friends who don't share their interests learn to accept these passions and even support them. By Season 12's "The Procreation Calculation," Penny rents the Batmobile from the 1966 "Batman" TV show for Leonard to ride around in for a day when she realizes the sacrifices he's making for their relationship. Rather than stereotype nerds as overgrown children who need to "grow up," the show reveals that true growth comes from developing empathy for others and seeing the value in what makes them happy. One could argue that the central theme of "The Big Bang Theory" is understanding.

Mrs. Wolowitz must remain unseen by the audience

The unseen character is a popular trope in TV sitcoms. Audiences never saw the face of Norm's wife Vera on "Cheers," and Niles Crane's wife Maris was always funnier by the way the "Frasier" characters described her than she would have been as a physical character.

In "The Big Bang Theory," the writers gave us Debbie Wolowitz, Howard's overbearing, overprotective mother who always seems to be off-screen. Voiced by Carol Ann Susi, Mrs. Wolowitz is initially used as a comedic figure who ridicules (and is ridiculed by) other characters. Based on how others describe her in the show, we learn that she is a very large woman with a mustache who was abandoned by her husband. She treats her grown son like a child and regularly engages in screaming matches with her daughter-in-law.

Over time, however, the writers make Mrs. Wolowitz more sympathetic. Certain episodes portray her as a lonely woman who loves her son and enjoys taking care of him. She develops a genuine friendship with Stuart Bloom (Kevin Sussman), who gains a greater sense of self-worth as her caretaker. After Susi passed away in 2014, her character also died in Season 8's "The Comic Book Regeneration," causing Howard and the other characters to grieve her loss. Although Debbie Wolowitz never appears on screen, Susi's performance and the other characters' reactions turn her into a surprisingly complex figure.

Stuart must always run the comic book store

For the most part, the characters of "The Big Bang Theory" are happy with their careers and get paid well. Even Penny becomes a successful pharmaceutical rep by the end of the series. However, one character always seems to be stuck in a love-hate relationship with his career — comic book store owner Stuart Bloom.

A recurring character on the show from the beginning, Stuart runs The Comic Center of Pasadena, giving the gang a place to hang out. However, he always seems lonely and dissatisfied with his life. We later learn he graduated from the Rhode Island School of Design and is a talented artist, but he ended up being the guy who sells comic books instead of the one who creates them.

Unfortunately, since Stuart's store becomes a regular fixture on the show, he gets stuck in a low-paying, unrewarding job. Even when the store burns down in Season 7's "The Status Quo Combustion" and Stuart accepts a job taking care of Howard's mother, his new career proves temporary. By Season 8's "The Comic Book Store Regeneration," Stuart reopens his store after Mrs. Wolowitz gives him enough money.

Fortunately, by Season 11, things finally pick up for Stuart. He hires Denise (Lauren Lapkus) as his assistant manager, and the two start dating after Denise finds Stuart's pop culture knowledge "hot." His new store also seems more financially successful than the first one, showing that even if he has to be the comic book guy, there's no reason he can't be happy doing it.

Parents must always behave badly

The characters in "The Big Bang Theory" have plenty of neuroses, but their idiosyncrasies don't just spontaneously appear. As we learn more about each character's backstory, we discover that many developed their complexes due to the way they were treated by their parents.

Leonard was emotionally damaged by his neuroscientist mother Beverly, who wrote a book, "The Disappointing Child," on the clinical way in which she raised him. Howard's father abandoned him, and his lonely mother keeps him in a state of arrested development by guilting him into never moving out of her house. Raj's parents put him in the middle of their arguments during their divorce. Even Sheldon reveals he once walked in on his alcoholic father sleeping with another woman, causing him to develop his habit of knocking three times on every door.

This pattern of poor parenting extends to other characters as well. Penny's mother was more focused on hiding her son's criminal background than on Penny's wedding in Season 10's "The Conjugal Conjecture." Bernadette's mother smoked during her pregnancy, stunting her daughter's growth. She later made Bernadette take care of all of her siblings, leaving her with a complex about having children of her own. And Amy's overbearing mother tries to stop her wedding to Sheldon in Season 11's "The Bow Tie Asymmetry."

Given all the neglect and mistreatment these characters received, it's no surprise that they found each other. The empathy and affection they display toward one another must be very healing.