Your answer seems fine though I might word it slightly differently. "No, I don't. If they do, they might not have any time to be with their family." However. If you are interviewing for a job, I might consider an addition to that statement. Occasionally projects might require additional night or weekend hours for a short period of time. Maybe a week or two. However, I have heard it said by a management expert that if your employees are regularly working more than 40 hours per week then you are likely understaffed or dealing with incompetence. I happen to agree with him though many managers and companies don't.