Racing has long been a big part of Colton Herta’s family life, so it was not much of a surprise when he took after his IndyCar-driving father and began racing go-karts as a boy.

What was a surprise, to him and everyone else: winning an IndyCar Series race six days before his 19th birthday. Herta, who still lives at home in Southern California with his parents, recently became the youngest winner in the history of the sport’s top level.

Herta led the last 15 laps to win a race on March 24 at Circuit of the Americas in Austin, Tex. It was only his third IndyCar Series race, but the victory was no fluke: He qualified to start fourth in the 24-car field, and he held off the pack after Will Power’s car broke down.

Herta’s father, Bryan, 48, won four races and drove in the Indianapolis 500 five times. He was at the track to call strategy for the scion of another racing family — Marco Andretti, grandson of Mario — and was stunned at how quickly his own son had won a race.