The paradox is suppose to be that no reincarnation has yet to ever live through the trials. They all have so far died, thus if they all have died, how could they have descendants. I want to say it's because they all have families that continue the line. It was stated that Ono is "playing his role" as the cousin and there will always be other people involved who are not cursed to die.
Hmmm I hadn't thought of it that way. Now I want to reread it again.
they can't stay together if one dies. Hasn't it already been mentioned that no couple has survived all the misfortunes?
oops, sorry, didn't see somebody already replied
I've been thinking, is it possible that the original couple did not stay together or were unfaithful? Those affected every 100 years are direct descendants. If that's the case it means that the original couple each had sex with women and later had children. If they had remained faithful or together this could not have happened. Or did their families force them apart and into marriage for the sake of heirs? But either way it remains the same, that those affected are direct descendants and wouldn't be alive if their predecessors had only been with each other. Even the strange teacher who is a spirit of the games wondered why no one questioned how there are direct descendants if they had only each other. （￣へ￣）