Deadline is reporting that HBO's Big Little Lies' Iain Armitage will take on the lead role, bringing to life Sheldon's growing up in Texas, and the interactions between he and the rest of his family. Parsons, who came up with the concept for the show, feels that it's a natural, largely due to The Big Bang Theory's writers providing such detail to the character over the past decade. "It just seems like a really wasted opportunity if you don't decide to explore the origin story with that," the actor related. "I mean, they've layered so many things in there that are ready to be drawn from."
Also cast is the part of Sheldon's born-again Christian mother, Mary, played on the regular series by Laurie Metcalf, but to be portrayed on the spin-off by the actress' daughter, Zoe Perry.
Still to be cast are the parts of Sheldon's twin sister, Missy; older brother George, Jr. (who we have not met yet), and his father, George, who had died prior to the events of BBT.
One of the reported reasons that the spin-off hasn't been announced yet is that negotiations for a two-year renewal of The Big Bang Theory are ongoing.
• The Big Bang Theory: Jim Parsons Talks The Sheldon Spin-Off
• Big Bang Theory Team Plans Young Sheldon Spin-Off