I don't believe that technically/legally, an interviewer can ask anything, especially in the nature of this question, about your personal life. It's one thing to ask someone if the follow the Reds or Bengals, but to ask them about a failure in their personal life? I find that very inappropriate. For all that interviewer knows, something tragic or devastating could have recently, or quite in the past, happened that the person assumes responsibility for, whether warranted or not. A job interview is NOT the place to air everyone's dirty laundry. It may have cost me the job, but I would have politely declined to answer about my personal, that it was not an appropriate topic for a job interview and had no bearing on my job, but that I would gladly answer the second part of the question, and then proceed to do so. I'm glad I declined an interview at UC for a CRC position.