He certainly had music in his DNA. His mother was an opera singer, and his father, Arvid, was a conductor. Young Mariss was introduced to the Riga Opera House early — perhaps too early.

“My father once took me to see my mother in ‘Carmen,’” he told The New York Times in 2005, “and in the first act, when they grab Carmen and take her to jail, I started shouting, ‘Don’t touch my mother !’”

He recalled sitting in on his father’s rehearsals at 3; sometimes he would wave a stick in imitation.

At the end of World War II Latvia came under the control of the Soviet Union, as it had been briefly before the Nazis arrived. As a teenager Mr. Jansons moved to Leningrad (now St. Petersburg), where his father became assistant conductor of the Leningrad Philharmonic, and began to study conducting himself at the Leningrad Conservatory.

In 1969, having impressed the Austrian conductor Herbert von Karajan during a master class in Leningrad, he won a scholarship to study in Vienna. He became Karajan’s assistant at three Salzburg Festivals, and in 1971 he was named associate conductor of the Leningrad Philharmonic.

Some Soviet artists defected during this period, but not Mr. Jansons.

“I had mixed feelings,” he told The Times in 1994. “St. Petersburg is a great city, with great culture. It gave me so much: my education. And although I thought, yes, this is a terrible dictatorship, I was never prohibited from working or traveling.”