“Is this your son?” they asked. “Is this the one you say was born blind? How is it that now he can see?”
The Jews put 3 questions to the parents, probably to confuse them and give their questioners the upper hand. The first 2 are relevant to the area of knowledge of the parents, but the last “How is it that now he can see?” is a foul-up on the part of the Jews, since the question follows on the concession that the man was formerly blind but now sees.
There are 3 groups of people to watch here: the Jews, the parents, and the man. The differences are interesting and educational.