As in other sports, brother combinations have played an important role in racing history, particularly at Indianapolis Motor Speedway. Before WWII, only three pairs of siblings competed in the Indy 500.
The first was Ralph DePalma, Indy’s first real superstar. His brother John raced in only one 500, Ralph’s winning year of 1915. He lasted only 41 laps. Ralph had another relative, his nephew Peter DePaolo, who won in 1925.
The next were the three Chevrolet brothers — Arthur, Louis and Gaston. Arthur drove in 1911 and 1916. Louis was a four-time starter. Gaston won in his second try in 1920, becoming the “first” Chevrolet to win at Indy.
Joe Russo finished fifth in 1934, but was killed at Langhorne, Pa., shortly after. His brother Paul was a 14-time starter, finishing fourth in 1957. Joe’s son, Eddie, ran at Indy three times.
When George Robson won in 1946, his brother Hal was in the lineup.
The next brothers were the Rathmanns. Jim won in 1960 and finished second three times. Dick’s best finish was fifth in 1956. He won the pole in 1958.
The most storied brother combo at Indy is the Unsers. It started with Jerry in the 1958 race. He was in the first-lap accident and didn’t complete a lap. He was killed in practice a year later.
Bobby Unser won the race three times (in three different decades) in 18 starts. Al Unser has one of the most impressive Indy 500 records. One of three four-time winners, he raced at Indy from 1965 until 1993. Sons of all three Unser brothers have competed in the 500.
Tom Sneva made 18 Indianapolis starts, winning in 1983. His brother Jerry ran five times with a 10th-place finish. Four-time winner Rick Mears raced with his brother Roger, who made two starts.
The Bettenhausen family has a long 500 lineage. Following father Tony’s 14 starts, Gary made 21 tries. His best finish was third. Tony, Jr. made 11 starts, finishing seventh in his rookie season.
Pancho Carter and Johnny Parsons are half-brothers who followed their successful fathers. Pancho drove in 17 races with a third-place finish and one pole. Johnny was a 12-time starter with three top 10s.
Bobby and Donnie Allison both interrupted their NASCAR careers to run two Indy’s each. Bobby had two DNFs, while Donnie finished fourth and sixth.
Michael Andretti led more laps than any non-winner in 500 history. The only driver in history to race against his father and his son at the Brickyard, he competed against his brother Jeff in three 500s.
Mike and Robbie Groff made six 500 attempts, but never had a top-10 finish, nor did they race in the same event together.
Two brothers currently racing are Buddy and Jacques Lazier. Buddy won in 1996, making 13 races that have been won by someone who had a brother race at the speedway.
The biggest brother boom came in  1981 when three brothers competed in the same race — Don, Bill and Dale Whittington.