Young Sheldon characters could someday toon up on The Big Bang Theory 

is Jim Parsons, who lends his voice as a narrator to the freshman spin-off about a pint-sized Sheldon Cooper. But if the producers have any say, grown-up versions of kid characters on

“There are young people in young Sheldon’s life we may someday meet as adults,” executive producer Chuck Lorre told reporters Wednesday. “We are all in love with young Billy Sparks [played by Wyatt McClure]. To see him walk into Pasadena would be a thrill if we get that right.”

Lorre even admitted they talked about creating an adult version of Georgie, Sheldon’s older brother played by Montana Jordan, for

And the dream guy to play him? “[Matthew] McConaughey!” quipped Lorre.

But Lorre dismissed any notion of a full-scale crossover night between the two CBS comedies. “I don’t think we are that organized. You have no idea of the chaos behind the scenes. That kind of coordination is not possible.”

will feature lots of guest stars who are often featured on

. “You have to remember this show takes place 30 years ago,” says executive producer Steve Molaro.

“It’s a smaller world that we live in, Houston,” added Lorre. “It’s not likely a Nobel prize-winning scientist will come through.”