• Becky and Ellie Downie (Great Britain; gymnastics): As 24-year-old Becky rounds out the end of her Olympic career in Rio, 17-year-old Ellie is just getting started and already proving that she's one tough cookie after a scary fall on the floor exercise last week. My sister and I are seven years apart, so I know how difficult that age gap can be, but this sport keeps their bond and support strong.

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  • Cate and Bronte Campbell (Australia; swimming): These swimming sisters are more often than not competing against each other in the pool but still working hard to win it for Team Australia, no matter what. Case in point: They both were on the same relay team that took home the gold in Rio in the women's 4x100 meters freestyle.

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  • Venus and Serena Williams (USA; tennis): Where there is tennis, there will be the Williams sisters, and the Olympics are no exception. We aren't sure if this will be the last time we see either one of them on the Olympic stage (both were eliminated early in singles and doubles play), but luckily for us, we don't have to always wait four years to see them in action.

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  • Liina, Lily, and Leila Luik (Estonia; marathon): The Estonian triplets (as they are called) have made history as the first set of identical triplets to compete in the Olympic games. Even more impressive, these 30-year-old marathon runners started seriously running at age 24.

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  • Courtney and Kelley Hurley (USA; fencing): This is not the Hurley sisters' first rodeo. Though they were the first set of siblings to qualify for Team USA for Rio, they are competing together for the second time in the Olympic Games. They were on the bronze winning team in the 2012 London Games. This year is a bittersweet one as Kelley contemplates retirement after Rio, her third Olympics.

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  • Aria and Makenzie Fischer (USA; water polo): This sport runs in the family as these two sisters are taking after their water polo–playing dad. Aria and Makenzie are also the youngest team members at only 17 and 19 years old.

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  • Margaux and Isabella Isaksen (USA; modern pentathlon): As Margaux enters her third Olympic Games (and possibly her last), she's more than thrilled to have her little sister Isabella along to start her own legacy in her first Games. In case you didn't know, the modern pentathlon combines fencing, pistol shooting, horseback riding, freestyle swimming, and cross-country running. Color me impressed!

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  • Julia and Katie Reinprecht (USA; field hockey): When your mom is a field hockey coach, how can you not be superstar players, right? These stick-swinging sisters are in Rio for their second Olympics, putting it down for the USA.

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  • Arina and Anastasia Rodionova (Australia; tennis): Like the USA's Williams sisters, the Rodionovas are all over the international tennis circuit playing doubles together in major tournaments. Rio is Anastasia's third Olympics and Arina's debut Games. Though they were knocked out in early rounds, we definitely haven't seen the last of them.

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  • Caroline and Carmen Marton (Australia; tae kwon do): The "Rio combat sisters" trained together for 26 hours a week so that they could come to Brazil and kick some butt. For Carmen, this is Olympics No. 3, whereas Caroline is just getting started.

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