Seeing a man blind from birth, the disciples ask Jesus who sinned—the man or his parents—that he was born blind. Their question assumes that the disability must be explained by a particular moral offense.
Jesus rejects both alternatives as the explanation for this man's condition.
The Hebrew Scriptures affirm that wrongdoing can have consequences, including effects extending through families and communities, but they also resist any simple equation between individual suffering and individual guilt. Job is the classic biblical protest against that simplification, and passages such as Ezekiel 18 emphasize personal moral responsibility.
The disciples' reference to the man's own sin despite congenital blindness has generated several theories, but the text does not explain exactly how they imagined that possibility.
The background keeps readers from attributing to Jesus the very assumption he corrects. The man's blindness is not presented as proof that either he or his parents committed a specific sin.
Jesus redirects the discussion away from assigning blame and toward what God is about to do, preparing for the sign in which physical sight also becomes a setting for spiritual revelation.