Greg Garber looks at America's sibling sensations competing in Athens:
Bryan: Twin destinies
The Bryan twins don't always get along, but they're united in their goal to win gold.
Dumais: Perfect harmony
Justin and Troy Dumais, although brothers, didn't start out as the best of friends.
Hamm: Leading the way
Paul and Morgan Hamm hope to take U.S. men's gymnastics back to the medal podium.
Kirk: Getting along swimmingly
Tara Kirk's resume suggested she was a more logical Olympic choice than sister Dana.
Smart: Making a point
Fencers weren't exactly common in Brooklyn where Erinn and Keeth Smart grew up.