Originally Posted by Shivercide

Back in medieval times, there was a man who was imprisoned in a tower by the king. On the last day before he was supposed to be put to death, the king went to see him and gave him an offer. He told the prisoner, "It's been many years since someone told me a riddle that has left me completely confused. If by the setting of the sun you can think of a riddle that I cannot solve, then you are a free man." The prisoner walked around his tiny tower room all day, trying to come up with a really good riddle. It was when he stuck his head out the window to get a breath of fresh air, that he thought of one. When the king returned, the prisoner walked over to the window, and pointed down to the courtyard, at a man who was selling vegetables. The prisoner then said, "Though I have no sisters or brothers, that man's father is my father's son. What relation am I to that man?" The king was not able to come up with the correct answer by the time the sun set, so the prisoner was granted his promise and set free. But what is the answer?