I was fired before at a bank, so I went on vacation to China for over a month. Then I found another job at a different bank. So I had about 3 months gap in between. When they asked me the same question. I just told them I need a vacation. For your situation, you could tell them that you need to take a trip to China to take care of family issues. Also you can add I want to challenge myself to work in different fields. Interviewer usually will not ask you deeper when you say family issues.