Although the question may seem innocent, and most of the time it will be, it is still improper, and may cause you to feel uncomfortable.
Whilst you must quickly decide whether to answer it or tactfully decline, you must remember that you are here to get the job. Regardless of how you perceive the interviewer, if you make him or her feel ashamed of his words and actions, you may well find yourself in a compromising situation.
Giving the company the benefit of the doubt for the duration of the interview, and then deciding later whether it's a place where you'd want to work may be the best option.
Is the question illegal?
The Equality Acts of 1998 and 2004, prohibit employers and potential employers from discriminating against anyone on the basis of:
Membership of the travelling community
Therefore, questions relating to any of these subjects could bring about criminal proceedings.
Handling illegal questions
Situations in which an insensitive or discriminatory question has been asked will need to be dealt with in the manner you see appropriate. Obviously, many variables will affect your response, but here are some examples of how to answer 'on-the-spot' inappropriate questions, such as “Do you plan to get married and have children?” or “Where were you born?”
Politely say that you do not wish to answer such an inappropriate question.
Answer the question by saying, “I'm sorry, I believe I missed the point, I do not understand the relevance of this question to my working career.”
Respond to the question without any reference to its appropriateness.
Ignore the improper question, and turn the focus around to the concern that lies behind the question. For example, you might say 'I think what you are asking is...', and then select the answer you wish the interviewer to know.
It is important to understand that although you would be justified in refusing to answer an inappropriate question, doing so might cost you the job. Therefore, the only question that remains is "Do I want to work in an environment that might subject me to such practices or assault my dignity?"
Remain in control
Knowing your rights and how to handle improper questions in interviews is of paramount importance. Going to the court of law might be extreme, but it has been known to happen.
As long as you are tactful, you will be in control. Answer in brief and move on to a new topic area, or ignore the question altogether and redirect the discussion towards a different subject