Fun Riddle to Mindfuck people

[KEN]

John's father is peter's father's only son.What is the relation between john and peter?
Prove It.

About the Past: I forgot to write in hurry: I discussed this with sethioz and we both did have a good time thinking on it and getting mindfucked :) we know it but we will give our answer after a while later when people give their answers hehe :)

[Sethioz]

i know, but i dont want to spoil the fun, lets see what others will say ehehe.

[thefinalrune]

Wouldn't they be parent and child?

John has a father.
Peter has a father.
Peter's father has only one son.
Therefor Peter is the son of Peter's father.


John's father is Peter's father's son, so Peter must be John's father.

[Sethioz]

lets not say if its correct or not, i want to see more ppl mindfucking themselves

[PinPoint]

father and son.

Johns father is peter
peter's father only had him, making him an only son

[siab]

They are father and son. If Peter's father only had Peter, then that makes Peter John's father because John's father is Peter's father's son.