Yoon Joon Suh and Yoon Eun Suh grew up as siblings but Eun Suh was in fact from a different family as there was a mix up at the hospital where she was born. The switch came to light when Eun Suh was involved in a car accident and it was discovered that her blood type was different from her parents. Eun Suh's life took a complete turn when the 2 girls were returned to their respective families. Soon after, the Yoon family left for the States and Eun Suh was left living in sordid condition with her real family in Korea. Years after, Joon Suh returned to Korea and by chance the two former siblings were reunited. (Source: DramaWiki)