BEVERLY HILLS  — There’s a risk trying to present The Big Bang Theory‘s difficult Sheldon Cooper as a 9-year-old genius, as is the case on the CBS prequel, Young Sheldon, due Sept 25.

First, there’s Jim Parsons’ ability to make a disagreeable person likable, says Chuck Lorre, executive producer of both comedies.

“Jim has a magical quality. Sheldon can be despicable (and) hard on his best friends. (But) the audience forgives him. Take those same qualities and ask a 9-year-old to bring that and that’s a brat,” Lorre told the Television Critics Association Tuesday. 

MORE: What to expect from your favorite TV shows

 

To that end, the younger Sheldon (Iain Armitage), who’s growing up in Texas in 1989, has “not yet become cynical. He has his idiosyncrasies. He’s a much more vulnerable and naïve character when we enter the story.” He also doesn’t yet like comic books.

In the series, young genius Sheldon is advancing grades in school, a source of some pride but mostly discomfort for him and his family. His mother, Mary, is played by Zoe Perry, the real-life daughter of Laurie Metcalf, who plays an older version of that character on Big Bang

Lorre, executive producer Steven Molaro and Parsons, who  narrates as the adult Sheldon, say Armitage (Big Little Lies) was a natural for the title role.

The producers first saw Armitage via an iPhone audition he recorded at his grandmother’s house in Georgia. “He made us laugh,” said Lorre..

Armitage said he hasn’t watched much of top-rated Big Bang, but he’s seen “a couple appropriate clips. I don’t watch that much TV, anyway.” And Big Bang “is aimed at a different audience than me.”

Parsons marveled at Armitage’s composure. “We have a lot more in common now than I would have had at the same age. I wasn’t mature enough at 9.”

And he doesn’t have much in common with young Sheldon, either.

“I was not an overly bright child. I was mediocre. I didn’t befuddle my parents. That came much later, with my sexuality,” he said. “Iain is much more in control as a human being than I was.”

Armitage interjected: “I’m not sure that’s true.”

Said Parsons: “You didn’t…