Riddle: A person went to a prison he said to the warden that he needed to talk to a prisoner. The warden said that he needed to be a relative of the prisoner. THe man said," I am a relative because 'brothers and sisters I have none, but that man's father is my father's son'" So how is the prisoner related to the man??
Answer: the prisoner's father is the man, so the prisoner is the man's son