What should we tell manager who wants to ask inappropriate interview questions?

Q. We have a manager who is really concerned about “fit” when we interview for his group. He wants to ask questions about hobbies, whether the candidate has a family and how that will affect the candidate’s ability to be at work. I’ve tried to explain that, due to discrimination laws, we should only ask questions based upon the job and its requirements, but he ignores me. What can I do?