But around that time, with little explanation, her parents ended her violin lessons. She continued with piano, however, and for the next decade was her brother’s primary accompanist. Already, it seemed, she was being directed away from a solo career and into a supportive role for Yo-Yo, now the world’s leading cellist .

In 1962, the same year as the Washington performance, their father, Dr. Hiao-Tsiun Ma, a conductor, musicologist and teacher, founded the Children’s Orchestra Society in New York. That orchestra will celebrate its 50th anniversary — there was a seven-year hiatus from the late-1970s to the early ’80s — with a gala concert at Carnegie Hall on Thursday, including Rimsky-Korsakov’s “Scheherazade” and works by Koussevitzky and Bruch.

When he founded the orchestra, Dr. Ma hoped that one of his children would take it over some day. That mission wound up falling to Yeou-Cheng, who in 1984 became the orchestra’s executive director even while working full-time as a developmental pediatrician at Albert Einstein College of Medicine . Her husband, Michael Dadap — a guitarist, composer and conductor — is the orchestra’s artistic director.

This is not the way Dr. Ma — Yeou-Cheng, that is — imagined her life in music unfolding when she was a child. She never considered taking over the orchestra following the retirement of her father in 1977 (which led to the hiatus). Everything changed when she met Mr. Dadap.

“Michael was a touring musician,” Dr. Ma, 67, said in an interview. “When we were courting, trying to decide what to do about family, I asked him if he was going to continue touring. He said he would really like to have either a music school or a children’s orchestra. He didn’t even know that I had this organization!”