The brothers who were separated in childhood in the drama "Triangle" are not an isolated case in k-drama plots. K-dramas are full of siblings who were separated at birth or during childhood.

The separation of siblings often raises the question of what it means to be a family.

In the case of "Triangle," Lee Bum Soo, Kim Jaejoong and Im Si Wan were sent to an orphanage after their father died and went on to live very different lives. One became a policeman, another a thug, and the third a rich man's son. None of them will be whole until they reunite.

Sometimes it works the other way. A character might think someone is his sibling and it turns out that he is not. In "East of Eden," Song Seung Hoon is close to his brother, played by Lee Dong Wook. But then he finds out that the two are not brothers. His real brother is someone else. That raises the question of who he should be loyal too. Is blood thicker than water? Or a lifetime of caring for each other?

And then there are the brothers from another mother.

Jung Il Woo rivaled his half brother for the affections of Lee Chung Ah in "Flower Boy Ramen Shop." It takes him almost the entire drama to realize that Lee Ki Woo's character is his sibling but that doesn't stop him from pursuing the girl.

And sibling confusion does not just happen to brothers. In "Rooftop Prince," Han Ji Min is fond of her stepsister who has always treated her cruelly and never considered her family. In a weird twist of fate the women turn out to be more than stepsisters. Jung Yu Mi is also the daughter of Han Ji Min's mom, so that makes them half sisters. The mom abandoned them both on separate occasions and coincidentally they were both raised by the same woman.

Things can get really complicated if a couple suspects they might actually be siblings separated in childhood. For a few episodes of "You're Beautiful," the plot hints at the possibility that Park Shin Hye's character is really the daughter of Jang Geun Suk's drama mom. Fortunately for the drama's love line that is not the case.

Being separated or switched at birth can be a bad thing but sometimes it works in a character's favor. In the Hallyu hit "Autumn In My Heart," Song Seung Hoon and Song Hye Kyo grow up together. Fortunately, she was also switched at birth, making it a little easier for them to fall in love.

Do you have a favorite drama involving siblings? Let us know.