In all fairness, this question is probably too out there for your typical legacy interview (unless Mom and Dad enjoyed watching motivational speakers and Simon Sinek TED talks (http://bit.ly/1w2ZyO5)). But I think what the question is getting at is very important. It's not enough to simply talk about what someone does or did to fill their time. Ask questions that challenge them to discuss why they did those things. Why do you love doing philanthropy? Why do you keep working long after you could have retired?
Getting beyond the WHATs and HOWs and uncovering the WHYs is the most important part of conducting a successful interview. For more on this subject, I wrote this blog post back in May of 2012: http://www.communicategood.com/blog/2012/05/rule-1-dont-tell-me-what-you-do