Too inquisitive of your hobbies:

During the time of interview, the interviewer will be in the more interested in knowing who you are, what you are etc. There is a fine line between genuine relationship building and fishing for information.

So always make sure that you use your discretion on this. If you have an overall good impression of the potential boss, it may be that he or she is truly interested in knowing the fact that you are heavily involved in charity work and he may be simply getting to know you. But on the other hand the intention of those questions may be in trying to determine whether you have too many commitments outside of work. In some cases the interviewer can’t legally ask if you are married or not or have kids, so at that time he may start digging into your personal life. This can be a clever way to understand how available you are.