Young Sheldon is now streaming alongside The Big Bang Theory on HBO Max, so we’re taking stock of the prequel series’ many nods, cameos and crossovers with the mothership.
First launched in September 2017, Young Sheldon fills in the details of Dr. Cooper’s upbringing in East Texas. The story starts off in 1989, and is told from the point of view of a more mature Sheldon, “who is older now [and] seeing his parents in a different light for the first time.” This altered perspective has allowed the spinoff to chart its own path and occasionally diverge from Big Bang canon without ever disrespecting what preceded it.
Whether you’re familiar with the prequel or simply curious, the following guide provides a rundown of all the ways the single-camera offshoot has paid homage to Big Bang, provided answers to some of our lingering questions (for starters, what’s a Bazinga?!), and painted a clearer picture of Sheldon’s relationship with his family, including his ill-fated father. Also featured are multiple Easter eggs, crossovers that took place after the mothership ended, and details about Sheldon and Amy’s future that were never disclosed on BBT. We’ve also included season and episode numbers for those who want to watch (or rewatch) select half-hours.
TVLine will continue to update this guide throughout Young Sheldon‘s run on CBS; the spinoff was previously renewed through Season 7. In the meantime, scroll through the following list to see if you’ve caught every tip of the hat to The Big Bang Theory, then drop a comment below.
THE FAMILIAL CASTING OF MARY COOPER
As is widely known, Laurie Metcalf’s real-life daughter, Zoe Perry, plays her younger counterpart on the CBS prequel.
THE CURIOUS CASTING OF GEORGE SR.
Before he was Young Sheldon’s dad, Lance Barber was Jimmy Speckerman, Leonard’s high school bully, in a Season 5 episode of The Big Bang Theory.
GEORGE SR.'S HEALTH
Sheldon’s father’s fate is predestined — and Young Sheldon is well aware of it. George Sr.’s mortality cast a shadow over the series’ third episode, in which Mary escorted her husband to the emergency room after he began complaining of chest pain. What was ultimately diagnosed as a minor heart attack gave the entire family a major scare, and served as a red herring for a tragedy that will ultimately befall the Cooper family.
PAGING NURSE DAVIS... OR IS IT NURSE ROBINSON?
Following five appearances on The Big Bang Theory as nurse Althea Davis, Vernée Watson guest-starred on two episodes of Young Sheldon as a different nurse, Nurse Robinson. The Fresh Prince of Bel-Air vet also played a nurse on Two and a Half Men, and currently co-stars as Gloria, yet another nurse, on Bob Hearts Abishola. (Suffice it to say, Vernée Watson is the glue that holds the Chuck Lorre Televisual Universe together.)
Sheldon’s beloved grandma was mentioned countless times throughout Big Bang‘s first eight seasons, finally appearing (in the form of June Squibb, no less!) in Season 9. Designing Women alumna Annie Potts would eventually take over the role, beginning with the spinoff’s third episode.
Sheldon’s childhood bully was mentioned in Seasons 3 and 5 of the mothership. He made his on-screen debut in Episode 1 of the spinoff, when he taunted the title character with his pet chicken Mathilda. Since then, however, Billy has been portrayed as more of a nuisance than a tormentor, and hasn’t given the future physicist reason to add him to his all-time enemies list… yet. (We’re still waiting on the day he shoves a Mexican peso up Sheldon’s nose.)
Those who aren’t familiar with the prequel might not know that Sheldon’s childhood friend, whose adult counterpart made an appearance during Big Bang‘s 12th and final season, was first seen on Young Sheldon, not the other way around. On Big Bang, we learned that Tam and Sheldon lost contact years after attending different colleges.
In the series premiere, we caught a glimpse of Bob Newhart’s alter ego demonstrating how to power a clock using only a potato. (Sound familiar?) In addition, a signed photo of Arthur Jeffries hangs on Young Sheldon’s wall.
Years before Dr. Cooper would befriend the renowned theoretical physicist, he would score an all-expense paid trip to Pasadena, Calif., where he and George Sr. attended an (off-screen) lecture by the wunderkind’s scientific hero…
That episode, Season 3’s 16th installment (“Pasadena”), found Sheldon and his dad at Sheldon’s future alma mater, the California Institute of Technology. In the tag scene, father and son stood in the doorway of the Caltech cafeteria, where Sheldon would one day convene with his good friends Leonard Hofstadter, Howard Wolowitz and Rajesh Koothrappali. (Watch the prophetic scene and read our post mortem with series co-creator Steve Molaro.)
TVLine was the first to confirm that the Big Bang alumna made an uncredited, voice-only cameo in Season 3’s 10th episode, “Teenager Soup and a Little Ball of Fib.” In the episode, Sheldon had a nightmare about an impending swim test in gym and found himself taunted by the bacteria-infested pool, which sounded an awful lot like Penny.
Cuoco was the first of Jim Parsons’ former co-stars to cross over to the single-camera offshoot. (Watch the scene and read our interview with Molaro.)
BLOSSOM? NEVER HEARD OF HER...
Mayim Bialik’s star-making role was referenced in Season 2, Episode 11 (“A Race of Superhumans and a Letter to Alf”), when Sheldon’s twin sister Missy pitched a number of potential boyfriends for her Cabbage Patch doll.
MISSY: “How do you think Celeste would look next to Joey Lawrence?”
SHELDON: “I don’t know who that is.”
MISSY: “He’s Blossom’s brother.”
SHELDON: “I don’t know who that is.”
MISSY: “It’s a show. She wears hats.”
Little did Young Sheldon know that his sister was referencing his future wife! (Funnily enough, The Big Bang Theory also name-dropped Bialik three years before she was cast as Amy.)
A PRECURSOR TO 'THE GORILLA EXPERIMENT'
Years before Sheldon forced Penny to ponder the question “What is physics?” and documented his findings, the pint-sized brainiac posed an experiment similar to Project Gorilla and used Missy as a test subject (also Season 2, Episode 11).
“If it’s funny, it’s a Bazinga!” That was the slogan for a novelty company introduced in Season 2, Episode 10 (“A Stunted Childhood and a Can of Fancy Mixed Nuts”), which at long last revealed how Sheldon came up with his signature catchphrase.
HE'S NOT CRAZY! HIS MOTHER HAD HIM TESTED!
“Bazinga!” might be the catchphrase most commonly associated with Parsons’ alter ago, but “I’m not crazy! My mother had me tested!” is a close second. Sheldon first alluded to said assessment in Season 2’s 14th installment (“David, Goliath and a Yoo-hoo from the Back”), when Georgie asked Sheldon if he was crazy after he confronted a much-older bully.
ONCE AN 'H-O TRAINIAC,' ALWAYS AN 'H-O TRAINIAC'
The boy genius was always loco for locomotives. In fact, the prequel’s first episode opened on a close-up of Sheldon’s model train set. (“I’ve always loved trains,” Adult Sheldon said. “In fact, if my career in theoretical physics hadn’t worked out, my backup plan was to become a professional ticket taker. Or a hobo.”)
Long before Penny reluctantly sang Sheldon’s favorite childhood lullaby while applying vapor rub (counterclockwise, lest his chest hairs mat!), Mary sang that soothing song to her germaphobic son in Season 1, Episode 13 (“A Sneeze, Detention and Sissy Spacek”).
SHELDON'S PERFECT PITCH
Grown-Up Sheldon loves to tell people that he has perfect pitch, which he discovered on Day 1 at Medford High. When it was suggested by music instructor Ms. Fenley — played by Melissa Tang, who previously guested on Big Bang as Mandy Chow — that he pursue music professionally, the 9-year-old answered, “No thank you. Musicians take drugs.”
SHELDON'S BATHROOM SCHEDULE
Leonard isn’t the only one who’s had to put up with Sheldon’s timetable for bowel movements. His anomalous scheduling is referenced by Mary in the prequel’s eighth episode (“Cape Canaveral, Schrödinger’s Cat and Cyndi Lauper’s Hair”) and was also a point of conversation in the aforementioned Season 3 installment “Pasadena.”
Two years later, in the Season 5 episode “A Suitcase Full of Cash and a Yellow Clown Car,” said timetable was shown in full for the first time.
THE FIRST RELATIONSHIP AGREEMENT
Long before Amy crossed any T’s or dotted any I’s, 10-year-old Sheldon drafted his very first social contract: the Cooper-Sturgis-Tucker Behavior Agreement, which clarified his own involvement in Meemaw’s relationship with his mentor, Dr. John Sturgis (in Season 1, Episode 22, “Vanilla Ice Cream, Gentleman Callers and a Dinette Set”). But wait, there’s more…
SHELDON'S FUTURE REVEAL
As Meemaw and Dr. Sturgis signed and dated the aforementioned document, our narrator revealed some rather monumental “Shamy” news: “I would go on to draw up such contracts throughout my life, with roommates, with my wife… even with my own children,” he said, confirming he and Amy would go on to have kids (plural!) after the events of The Big Bang Theory.
Four years later, in the Season 5 episode “A Suitcase Full of Cash and a Yellow Clown Car,” Sheldon mentioned that Amy eventually stripped him of his comic book allowance to start a college fund for their children.
THE HOT BEVERAGE OF COMFORT — AND ANOTHER FUTURE REVEAL
In Season 3’s 12th installment, the “hot beverage of comfort” became Sheldon’s “go-to method of dealing with someone in emotional distress,” our narrator revealed. “And it always worked… except when my wife was in labor, where it was suggested that I throw it in my own face.”
When George Sr. stumbled upon Sheldon making tea for fellow pint-sized genius Paige, he told his son that he was proud of him. That was all the reason Sheldon needed to continue with this method for years to come.
'A REAL EYE-TALIAN TREAT!'
Sheldon first revealed his favorite childhood meal — spaghetti with cut-up hot dogs — to Penny in the Big Bang episode “The Spaghetti Catalyst.” On Young Sheldon, the pasta dish is Sheldon’s designated Thursday-night dinner. He even attempted to make it for himself in the Season 3 finale. (In Season 5, Episode 4, we saw Mary prepare the meal for the entire family.)
MARY'S NASTY HABIT
In Big Bang‘s Season 2 premiere, a drugged-up Sheldon disclosed to Leonard that Mary used to smoke in the family car. Her nasty habit carried over to the prequel, first when Sheldon’s mom was caught smoking while stressing over the boy genius’ education (in Season 3, Episode 21, “A Secret Letter and a Lowly Disc of Processed Meat”), then again for pleasure alongside Youth Pastor Rob (in Season 5, Episode 11, ” A Lock-In, a Weather Girl and a Disgusting Habit.”)
DR. TIRE: AN ORIGIN STORY
Georgie’s adult counterpart was introduced in the penultimate Season 11 episode of Big Bang, at which point it was revealed that Sheldon’s older brother owned a successful chain of tire stores. What followed was a Season 2 installment of Young Sheldon (“An 8-Bit Princess and a Flat Tire Genius”) that saw Georgie take a part-time job at Herschel Sparks’ auto body shop and discover an affinity for tires. The rest is history.
SHELDON'S LOVE OF COMIC BOOKS
Tam is singlehandedly responsible for inspiring Dr. Cooper’s eventual wardrobe, as well as his weekly visits to Stuart’s comic book store. Sheldon’s childhood friend first introduced him to comics in Season 1, Episode 4 (“A Therapist, a Comic Book and a Breakfast Sausage”).
SHELDON'S STAR TREK FANDOM
Our first glimpse at Dr. Cooper’s fandom comes thirty or so years before he’d appear in a documentary honoring the late Leonard Nimoy. In Season 1’s ninth installment (“Spock, Kirk and a Testicular Hernia”), Shelly explained to Meemaw that “Spock is half-human and half-Vulcan” and “ashamed of his human side… That’s why I identify with him.” (Little did he know that he’d one day possess a Cheesecake Factory napkin with Nimoy’s DNA!)
SHELDON'S LORD OF THE RINGS FANDOM
Years before a Lord of the Rings film prop threatened to tear him and his friends apart (in the classic Big Bang episode “The Precious Fragmentation”), Young Sheldon dove into the writings of J. R. R. Tolkien and had dreams where he, too, was transformed into Gollum (in Season 3, Episode 4, “Hobbitses, Physicses and a Ball with Zip”).
THE NOBEL PRIZE
The Season 2 finale tied directly into the mothership’s series finale. Immediately after Big Bang‘s Sheldon accepted the Nobel Prize in physics, Young Sheldon circled back 28 years to find Sheldon invite the entire school to a party for the 1991 Nobel Prize announcements. Unfortunately, no one showed.
“In that moment, I felt like a neutrino, destined to be alone forever,” Adult Sheldon narrated. “Thankfully, I was wrong,” he said, as younger versions of his future friends were shown, one by one, with Easter eggs aplenty…
The asthmatic Leonard was seen in his signature red robe with an inhaler on his desk.
Wyatt’s “little slugger” had a baseball and a bat near her bedside. On her wall was a cowboy hat to represent Nebraska, as well as a poster of Los Angeles, suggesting that she already had dreams of becoming an actress.
Howard was in his bedroom, donning his customary silk PJs. To his right was a table of magic tricks and props. (Mrs. Wolowitz also made a voice-only cameo, telling her son to “put away the fakakta game” and get to sleep.)
Howard’s future wife had a microscope on her nightstand to represent her interest in microbiology, as well as a trophy and a sash to represent her days as a child beauty-pageant contestant.
Raj was still in India. A stuffed tiger on his bed represented the Royal Bengal Tigers, while the telescope to the right of his desk foreshadowed his future career as an astrophysicist.
Last but not least was Sheldon’s future wife, who was wearing one of her old-fashioned nightgowns and up late reading — what else? — Little House on the Prairie. (Watch the scene and read our post mortem with Molaro.)
FUN WITH FLAGS
In the Season 3 finale, Sheldon made a videotape to convince Mary to let him go to college. Behind him was a chalkboard, the writing on which mirrored the writing on the whiteboards used as a backdrop for Sheldon and Amy’s long-running web series.
In the Season 4 premiere, Jim Parsons was reunited with Mayim Bialik, who reprised her Big Bang Theory role as Sheldon’s wife, Dr. Amy Farrah Fowler, in a voiceover. As the Cooper family gathered in the backyard to commemorate Sheldon’s graduation from high school, as well as twin sister Missy’s graduation from sixth grade, Sheldon the Narrator (voiced by Parsons) said that “it was the best graduation party I had been to… until we had one for my son, Leonard Cooper.
“I wanted his name to be Leonard Nimoy Cooper, but Amy wouldn’t let me,” he revealed. That’s when Bialik chimed in as Sheldon’s better half and said, “Be lucky I let you name him Leonard.” What followed was the exchange of “I love you’s,” before the episode cut to black.
Read our post mortem with co-creator Steve Molaro here.
Sheldon’s mortal enemy was first referenced in Season 4 of the Big Bang Theory prequel, when TV’s Wesley Crusher caught Missy’s eye.
MISSY: “Wil Wheaton’s cute.”
SHELDON: “If you like him, you should watch Star Trek with me.”
MISSY: “He’s not that cute.”
PROFESSOR PROTON APPRECIATION SOCIETY
In Season 4, Episode 11, Sheldon tried (and failed) to make friends at East Texas Tech by starting his very own club in honor of the beloved TV personality.
In Season 4, Episode 13, a new tradition was born when Sheldon proposed a science-based car game to his mother: “I’ll say an element starting with the letter A, then you repeat that and add one starting with the letter B.” As our narrator would explain, this tradition “would eventually bring countless hours of joy to Leonard on our drives to work. Much like my mother, he never beat me.”
GEORGE SR.'S DEATH FORESHADOWED (AGAIN)
In Season 4, Episode 17, “A Black Hole,” our omniscient narrator says he wished he’d had more time to tell his father how he felt about him before he died:
We often regret the things we don’t say. There’s a lot of things I wish I had said to my dad while he was around — that I appreciated him, that I loved him — which is why I am grateful for the times I did tell him how I felt.
GEORGE THE ADULTERER
The Season 4 finale established the family patriarch’s potential fall from grace, planting the seeds for an extramarital affair between George and recently separated next-door neighbor Brenda Sparks. Season 5 continues to hint at something between them, though the neighbors have yet to act on their obvious connection (as of Season 5, Episode 2).
Of course, George’s adultery was predestined. In a Season 10 episode of Big Bang, Sheldon confided in Penny that the reason he always knocked three times before entering a room was because he walked in on his father with another woman when he was 13 year old.
SHOW ME THAT SMILE AGAIN
Dr. Cooper first struggled to flash a grin in Season 2, Episode 4, when Raj was profiled for People magazine. In Young Sheldon Season 5, Episode 4, Sheldon found it difficult convincing George Sr. that he was happy having his own bedroom, separate from twin sister Missy.
SHELDON'S USE OF THE WORD 'COITUS' — AND HIS NO-WHISTLING POLICY
During Season 5, Episode 6, “Money Laundering and a Cascade of Hormones,” Adult Sheldon revealed why he’s always referred to sex as “coitus” on Big Bang.
“Every culture has their taboos,” he explained. “In the Ukraine, it’s rude to whistle in doors — and they’re correct. Not a fan,” he pointed out, reinforcing his no-whistling policy first cited in BBT Season 2.
“In our society, any discussion of human reproduction seems to be so upsetting that it causes chaos,” he continued. “Even the word ‘sex’ provokes an uncomfortable reaction. I thought ‘fornicate’ might work, but that seemed too judgy.”
It’s at that point that the 11-year-old reached for his thesaurus to find an alternative, and that’s when he landed on the perfect word — “a word so bland and clinical that it would be impossible to take offense to it.”
SHELDON'S DISDAIN FOR ENGINEERING
The Big Bang Theory‘s Simon Helberg reprised his role as Howard Wolowitz in a voiceover capacity during Season 5, Episode 7 — “An Introduction to Engineering and a Glob of Hair Gel” — which told the origin story of Sheldon’s “complicated relationship with engineering.” (Watch a clip here.)