North Korea's Kim Jong Un has hit the big 4-0 - or at least, that is what people suspect. The leader of the secretive state has never actually revealed his birthday, leaving North Korea watchers to puzzle out when it actually takes place. If they are right, he hit the milestone age on Monday, the same day official pictures were released of him and his daughter visiting a chicken farm. The low-key day stands in stark contrast to those of his predecessors. In fact, the birthdays of his father Kim Jong Il and grandfather Kim Il Sung - large, national celebrations during their time in power - are still marked by holidays to this day.
