Asking Interviewer About Family

I know it is poor form and bordering on illegal for the interviewer to ask the interviewee about family situations(wife, kids, etc.) What about the reverse direction? It is poor form/unethical for the interviewee to ask the interviewer about their family, specifically if the interviewer is going to be the interviewee's supervisor? I am married and have three young children and have had bad experiences with supervisors who have not had children.

Specifically, all things being equal I would rather work for somebody who understands that I don't want to support late afternoon meetings on certain days because kids have soccer practice and that sometimes I will just want to take a day off and spend it with the kids. I find people who have had children at some point to be more understanding.

Any thoughts?