A question : are you in the Computer Science field?

While I think that the way you would answer may work beautifully in other fields, we also have to think about the employer's best interest and the field we're talking about here.

Employer's best interest, across most if not all fields, is primarily to hire people that have skills that will be useful in creating advantage of the company as a whole. In the case of Computer Science field, then, having an employee that answers that particular interview question with how he/she has contributed to open source and/or created side projects will have higher probability to create more value for the company than an employee that answers with how he/she is a great parent or how he/she's working in a non-profit of unrelated field.