>>Actually, the Jews believed the sins of the father would be visited on his children.
That is one belief, but they asked if he had sinned (specifically) so he must have existed before he was born, or how could he have sinned?
There is no sin in Heaven so that is impossible. The Jews believed in transmigration of souls which is basically reincarnation. So you would be punished for something you did in your previous life. Messed up stuff.