The disciples seemed more interested in the
cause of this man's blindness than ministering
to him.

They asked Jesus who had sinned, he or his
parents. Since the man had been born blind, to
assume it was the result of his own sins would
have meant that the man had sinned in some
previous existence.

Some of the teachers had taught the doctrine of
reincarnation of the human soul. The disciples
must have learned about that teaching.