See the instructions here - https://docs.moodle.org/33/en/Questionnaire_Personality_test#Organization
To be a parent, the question must meet the requirements of that link.
mike
Close, but I think that Mike meant to send this link:
https://docs.moodle.org/33/en/Questionnaire_Conditional_branching
(maybe)
The two links are displayed adjacent to each other.