Brigitte Xie reads music, can play Beethoven’s Sonatina in F Major and has won a spot to perform at Carnegie Hall in New York. She is four years old.

Brigitte’s feet dangle above the ground when she sits on the piano bench, her hands moving gracefully across the keyboard.

With long brown hair in a ponytail and bow, she cast her dark eyes shyly downward when her mother, Nicole Sun, asked if she likes piano and if it was fun. “Yeah, fun,” Brigitte replied...