NASHVILLE — Kelly Clarkson knew she'd found her single when she noticed her two stepchildren singing Heartbeat Song around the house.
"They loved that song," Clarkson says of 13-year-old Savannah Blackstock and her brother, 8-year-old Seth, her husband Brandon Blackstock's children from his first marriage. "So we were like, 'Maybe we should go with the one they keep singing.' "
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