Transcript for A who's who of family members in the North Korean Kim family dynasty

The secret family tree of the Kim dynasty starts with Kim Il sung North Korea's founder they're great leader his offspring Kim Jong-Il. This deemed as the dear leader known for his bizarre haircut and pension for jump suits and platform shoes. But it is the third generation of the blood line where three young Brothers first appear. And it is the oldest Kim Jong Nam. Who is destined to one day lead. But the story most Americans don't know is how Kim Jong-un beat out two older Brothers to win the North Korean game of thrown us. But to understand the tail of the Brothers you first have to understand the tale of their mothers. Teams are not his mother was the first and vehicle wife of until hill and north Koreans differentiate the real life as a first wife and it anybody that comes after is this kind of a mistress. And in fact it's a mistress who gives birth to the current North Korean leader Kim Jong and so just how did this kid. And up as the supreme leader of North Korea. That older half brother Kim Jong Nam was taken out of the running managers ill advised attempt to sneak into Disneyland. His humiliating fall from grace leaves a huge opening on the other side of the family tree at the sons of the mistress. Condolences mother IO. I hear wasn't very ambitious woman and that once Kim Jong Nam but Cole ads and that's very embarrassing situation sneaking into Japan. That she capitalized on that and use that to promote her children. The logical next son in line is Kim Jung news older brother to control. But he would be the next domino to fall. Also on done by a fixation with a western culture. Namely the music of Eric Clapton he embarrassed the regime after he was repeatedly caught sneaking in that Clapton concerts. He does have a right temperament characteristics that's what he's fall though thought. That leaves the path clear for the youngest son Kim Jong-un beat only one not to publicly embarrass his father. Had a little bit of a tough streak in him and that's what his father liked that he was strong that he acted like me and soon enough. It's clear for the world to see. Kim Jong-un is position to be the future ruler of North Korea.

This transcript has been automatically generated and may not be 100% accurate.