Ask HN: How to deal with inappropriate interview questions?

A while back I had an interview with a fairly well known startup for an internship. The interviewer asked me a few personal questions - what did my parents do, do I have any siblings, what is my relationship status, whether or not my SO would be willing to move, etc. At the time I was a little creeped out but I didn't think much of it since I ended up taking an offer somewhere else.

<p>Now it's about the time that I'm going to start looking for a full-time job and I was wondering what I should say if that situation comes up again. If I say "sorry, I don't feel comfortable answering these questions", I'm afraid they might think I'm being prudish or something. I know startups are quite casual, but are these types of questions normal?