Sheldon Cooper's Journey
Young Sheldon began with Sheldon Cooper at nine years old and starting high school as a freshman, and The Big Bang Theory ended with the genius at 39 years old, so there are plenty of years to cover over the two television shows.
Jim Parsons as Sheldon Cooper in The Big Bang Theory season 1
As a child prodigy, Sheldon entered college when he was 11, graduated at 14, and received his first Ph.D. when he was 16 at the California Institute of Technology (Caltech). Following that massive accomplishment, the protagonist became a visiting professor at the University of Heidelberg in Germany. Sheldon was also the youngest person to receive the Stevenson Award (at the time).
Jim Parsons as Sheldon Cooper standing in front of a white board wearing a blue suit in The Big Bang Theory season 11
By the time the first season of The Big Bang Theory rolled around, Sheldon was a senior theoretical physicist at Caltech, where he worked alongside his friends — Leonard Hofstadter, Howard Wolowitz, and Rajesh Koothrappali. Sheldon was roommates with Leonard, and he later met and fell in love with Amy Farrah Fowler, a neuroscientist. It took the couple a long time to become official, and then they married in the season 11 finale of The Big Bang Theory. The series ended with Sheldon and Amy being awarded a Nobel Prize for their Super-Asymmetry Theory. Narration in Young Sheldon also revealed that the couple eventually had kids, including a son named Leonard.
Sheldon and Amy.
Family Dynamics
Sheldon's mother, Mary Cooper, is played by Laurie Metcalf in The Big Bang Theory and by Metcalf's daughter in real life, Zoe Perry, in Young Sheldon. Following the spinoff prequel, Mary becomes a widow when her husband and Sheldon's father, George Cooper, died in the mid-1990s. She frequently appeared in the CBS sitcom when she would visit Sheldon in California or when he would occasionally visit her in Texas. Plus, Sheldon would often talk about her throughout the series. Later in The Big Bang Theory, Mary starts seeing Leonard's father, Alfred, much to Sheldon and Leonard's dismay.
Mary Cooper talking to Sheldon in Young Sheldon
As mentioned above, George Cooper Sr., played by Lance Barber in Young Sheldon, died when Sheldon was 14 years old in 1994. He passed away from issues related to his weight, which left the family devastated. The CBS spinoff prequel series has yet to catch up to the year that George died. But if the network keeps on renewing the show for more seasons, it is possible that fans will get to see the patriarch's death and the Cooper family's reactions to losing their father and husband.
Lance Barber as George Cooper
The eldest Cooper child, George Marshall 'Georgie' Cooper Jr., is played by Montana Jordan in Young Sheldon and was portrayed by Jerry O'Connell in The Big Bang Theory. As seen in recent seasons of the spinoff, Georgie dropped out of school when he was 17 years old to work in sales, which set up his future as the owner of a tire store chain, Dr. Tire, as seen in the popular CBS series. Georgie also started dating Mandy McAllister when he was 17 and she was 29 (they both lied about their ages). She got pregnant, and he later proposed to Mandy, and she said yes.
Jerry O'Connell as Georgie Cooper in The Big Bang Theory Season 11 Episode 23 and Montana Jordan as Georgie Cooper in Young Sheldon season 6 episode 13
Other Characters
Sheldon's twin sister, Missy Cooper, is the exact opposite of him, as seen in both Young Sheldon, where she is played by Raegan Revord, and The Big Bang Theory, where she is portrayed by Courtney Henggeler. Unlike her brother, Missy is not a genius and has a better grasp of social cues. Following the events of the spinoff prequel, Missy gets married twice and has four children. In the pilot episode, Sheldon mentioned that his twin sister worked as a host at Fuddruckers.
Raegan Revord as Missy in Young Sheldon and Courtney Henggeler is Missy Cooper in The Big Bang Theory
Sheldon's grandmother, Connie Tucker, affectionately nicknamed Meemaw, is played by Annie Potts in Young Sheldon and by June Squibb in The Big Bang Theory. Meemaw is Mary Cooper's mother and one of the people that Sheldon feels the closest to in the world. Thankfully, she remained alive throughout the course of the CBS comedy show. But Meemaw only appeared in one episode, and she did not attend Sheldon and Amy's wedding in the season 11 finale of The Big Bang Theory.
Meemaw in Young Sheldon
Unlike every other character on this list, Many McAllister did not appear in The Big Bang Theory, nor was she mentioned by name. However, Emily Osment's Young Sheldon character might have been indirectly referenced when the other figures in the CBS sitcom television show discussed Georgie's long list of ex-girlfriends and ex-wives. Although the series never confirmed Mandy's fate, it is more than likely that she and Georgie married (which will probably be shown in a future episode of Young Sheldon) but divorced sometime after the spinoff prequel.
Mandy in Young Sheldon in front of books