Questions About Background of Minor Child(ren)

I work for a public school district and I know there are many teenagers who have criminal backgrounds.  May I ask on the application if there are any minor children who are under suspension / expulsion status from a public or private or have been found guilty of a felony or an act that would be considered a felony of committed by an adult?  Can I use that information to reject an application?  I just don't want drug dealers or sex offenders in my property, whether they are 14 or 114....