INDIANAPOLIS – For the second time since 1976, there will be two sets of siblings on the U.S. Olympic team in swimming.

One set is Alex and Gretchen Walsh, and the other Aaron and Alex Shackell of Carmel.

Alex Walsh has a silver medal in the 200-meter individual medley from the 2021 Tokyo Olympics, and again made the team in that event. Gretchen set a world record in semifinals of the 100-meter butterfly in the Olympic Trials at Lucas Oil Stadium, and also made the team in the 50 and 100 freestyles and at least two relays.

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It is the Olympic debut for both Shackells. Their father, Nick, was a British swimmer at the 1996 Atlanta Olympics.

Aaron, 19, won the 400 freestyle at the trials. Alex, 17, was second in the 200 butterfly and made the relay pool for the 4x200 freestyle by finishing sixth.

The Shackell siblings went 3-for-3 in making a Team USA: Andrew, who is Alex’s twin, qualified for August’s Junior Pan Pacific meet at Melbourne, Australia, in the 4x200 freestyle relay.

In 2004, the U.S. Olympic team also had two sets of siblings: Dana and Tara Kirk, and Klete and Kaylyn Keller. Before that, it hadn’t happened since 1976, featuring Steve and Bruce Furniss and Shirley and Jack Babashoff.

Joining the Olympic staff is the Shackells’ coach, Chris Plumb. Swimmers trained in a domestic camp at Cary, N.C., then headed to Croatia ahead of the Paris Olympics.

“I think they’re thriving in this environment,” Plumb said. “Obviously, they’re incredibly competitive. When you get a group of competitors together, the bar is raised.”

Aaron has prelims of the 400 freestyle July 27, and, if in the top eight, the final that night.

Alex is scheduled for prelims and semifinals of the 200 butterfly on July 31. On Aug. 1, there are prelims of the 4x200 freestyle relay. If she makes the final of the 200 fly, she would have 75 minutes before the relay, if among the four swimmers chosen.

U.S. siblings at the same Olympics

>> London 2012. Haley Anderson won silver in 10-kilometer open water and sister Alyssa gold in 4x200 freestyle relay.

>> Athens 2004. Klete Keller won gold in 4x200 free relay and bronze in 400 freestyle. His sister, Kalyn, was fourth in 800 freestyle. Tara and Dana Kirk were the first set of sisters on the same U.S. Olympic team. Tara won a silver medal in 4x100 medley relay.

>> Montreal 1976. Jack Babashoff was silver medalist in 100 freestyle. Shirley Babashoff won memorable upset gold in 4x100 freestyle relay and four silvers. She was tagged “Surly Shirley” for accusing the East Germans of doping, then was vindicated when all of her suspicions were later confirmed. Bruce Furniss won two golds, setting a world record in 200 freestyle. Steve Furniss, after a bronze in 200 IM in 1972, was sixth in 400 IM.

>> Munich 1972. Lynn Colella was silver medalist in 200 butterfly. Her brother, Rick, was fourth in 200 breaststroke. A five-time masters swimmer of the year, he won bronze four years later.

>> Los Angeles 1932. Brothers Mailoa and Manuela Kalili, native Hawaiians, made up half of the silver-winning team in 4x200 freestyle relay.

>> Paris 1924. Hawaiian brothers Duke and Samuel Kahanamoku were separated by 12 years. Duke, then 33, and Samuel went 2-3 in 100 freestyle behind Johnny Weissmuller to complete a medal sweep. Duke, who popularized the sport of surfing, had won two medals in 1920 and two in 1912.

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>> Antwerp 1920. Warren and Pua Kealoha were also Hawaiian brothers. Warren won the 100 backstroke at this Olympics and repeated in 1924. Pua won gold in 4x200 free relay and silver in 100 free.

Contact IndyStar correspondent David Woods at dwoods1411@gmail.com. Follow him on Twitter: @DavidWoods007.

This article originally appeared on Indianapolis Star: Aaron, Alex Shackell on rare list of sibling swimmers in same Olympics