A couple of ideas popped up:

#1: Is either or both of the kids the offspring of someone who works in this secured building?

#2: Keeping in mind that having sex is not a crime and granting that only the age of the participants and the public place are problematic, what would you do if you saw the child of an acquaintance shoplift an item - let's say, an expensive item - at a store? Would you tell?