The way I heard the story is: Two men were hunting in the woods, when they spotted a man hanging dead up in a tree. The 1st man says “Brothers and sisters I have none, but that mans father, is my fathers son”; what is the relationship between the 1st man and the dead man?
The speaker has no brothers (or sisters) so he is the only son of his father. Therefore “my father’s son” is “me”. Therefore “that man’s father is me”. Therefore the hanging man is his son.
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