The interviewer may be prying to find out about your
religious or ethnic background, so stick to
professional organizations when answering this question.
This question may be asked to discover prejudice
on your part.
This question is in the "fuzzy" area of lawfulness.
You do not have to be specific about which family members
are supportive. The employer may be trying to get you to
tell whether you are married or have children. Offer a
brief answer.