"The Big Bang Theory" lasted for 12 successful seasons, and during that time, the sitcom brought in several characters from Sheldon Cooper's (Jim Parsons) life. His mom, brother, and sister all show up for on-screen roles, and his deceased father gets a mention. That said, not everyone who impacted Sheldon gets acknowledged in the nerdy sitcom. Paige Swanson (McKenna Grace) from "Young Sheldon" doesn't appear on "Big Bang Theory," even though she was a notable part of his coming-of-age years, while Dr. John Sturgis (Wallace Shawn) is also ignored in spite of having dated Sheldon's Meemaw (Annie Potts) and mentored him.
Case in point: Sheldon's Nobel Prize speech in the "Big Bang Theory" finale made the cast cry, proving that it's an emotional moment. The scene sees the socially awkward physicist thank most of the important people in his life for supporting him throughout the years, marking a rare expression of gratitude from the character. However, Sheldon doesn't mention Sturgis during his big speech despite the influence he had on his childhood and scientific development back in the day. Keeping that in mind, there's one scene on "Young Sheldon" that suggests the titular boy genius doesn't respect Sturgis all that much, thus negating any need to mention him on "Big Bang Theory."