The king dies. A call goes out to locate his long-lost son, who ran away years ago. Two men show up, both claiming to be the son. It has been a long time, and the king's advisors no longer recognize the man. One of them suggests that each man do a blood test to determine which one is the true heir. The first man agrees, but the second one refuses. The king's advisors announce that the second man is the true heir. Why?
NOTE: The correct answer has been guessed. To read it, see the comments section.
Lateral Thinking Puzzlers by Paul Sloane has lots of classic riddles, clues and answers. Click here to order it.