Kim Jong Un is the third and the youngest son of Kim Jong Il, and the second son between him and one of his mistresses, an ethnic Korean dancer born in Japan named Koh Young He, who died in 2004 while being treated in Paris for cancer.

Officially born in 1982 (Kim Il Sung and Kim Jong Il were 'officially' born in 1912 and 1942, respectively), Kim Jong Un speaks English, German and French to varying degrees, having spent 2 years at international schools in Switzerland during his youth.

Kim Il Sung died in 1994 after grooming Kim Jong Il for 20 years as his successor. During the last 10 years of Kim Il Sung's reign, Kim Jong Il ran North Korea's day to day operations as its de facto prime minister.

By contrast, Kim Jong Il died in 2011 after grooming Kim Jong Un for only 1 year as his successor.

The brevity of the latter apprenticeship was due to Kim Jong Il having begun to seriously plan for succession only after suffering a stroke in 2008, as well as the substitution of Kim Jong Un as heir apparent after Kim Jong Il's oldest son, Kim Jong Nam fell from grace after getting caught trying to sneak into Japan with a fake passport to visit the Tokyo Disneyland (Kim Jong Il's second son, who is Kim Jong Un's older brother, was deemed too soft and therefore never in the race).

Since inheriting the ruling regime from his father, Kim Jong Un has purged it, even killing his own relatively reform-minded uncle, Jiang Son Thaek, and surrounded himself with his own loyalists. He also has focused on advancing the nuclear weaponry and long range missile programs of the North Korea's military, which he joined hastily in 2010 at the humble rank of a 4-star general.

How the Juche idea evolves to make room for Kim Jong Un remains to be seen.