Ko Kyong-taek was born on the island in 1913 and lived there until he moved to Japan. His daughter Kyong-hui later married then-North Korean leader Kim Jong-il. Ko's background in what had become South Korea was swept under the carpet. The location of his grave was so far unknown.

The graves of North Korean leader Kim Jong-un's maternal grandfather and great-grandfather have been discovered on Jeju Island.

But there is some propaganda mileage in the home of Kim Jong-un's maternal family. On April 3, 1948, Jeju was the scene of a communist revolt that ended with a bloody crackdown. Many people headed to Japan to escape the bloodshed.

Under North Korea's bizarre clan-based communism, Kim Jong-un draws his legitimacy from his direct descent from nation founder Kim Il-sung, what is reverently called the "Baekdu bloodline" after Kim Il-sung's alleged birthplace. But there is also a respected "Halla bloodline" of revolutionaries, borrowing the name of the mountain in middle of Jeju, into which his ancestry could by some stretch be shoehorned.

Records show Ko Kyong-taek moved to Osaka in 1929, long before the uprising, and worked in a munitions factory. He fathered one son and two daughters in Japan, including Ko Kyong-hui. In 1962 he was arrested for human trafficking and deported, choosing North Korea over the South.

His daughter joined the Mansudae dance troupe, where she caught Kim Jong-il's eye in 1971. The two had three children -- Jong-chol, Jong-un and Yo-jong. Ko died of breast cancer in France in 1984.

Her older brother, Dong-hun served as a North Korean diplomat in the 1990s, while her younger sister Yong-suk defected to the U.S. with her husband in 1998 after living in Geneva, where they managed Kim Jong-il's secret funds.