What often can be seen:

Child: Why? - question
Parent : Because ... - answer
Child: Why answer? - more questions
Parent: Because ... - more answers
Child: Why? - even more questions
Parent: I don't know, stop asking questions.

What ideally would happen:

Child: Why? - question
Parent : Because ... - answer
Child: Why answer? - more questions
Parent: I'm not sure. Let's find out together!