I have rules for myself, but not for my peeps. They can do what they please, unless I'm trying to make them do something specific at the moment (like training them in their career).

Rules for myself vary by family. It might be something like "First-born always inherits house" or "Children named after ancestors" or "Stay poor!" or something like that. Basically a rule like this would govern what the family tree would look like or what the family's "theme" would be.

In some families I'll do an experiment like making everybody lazy or something.

Recently I've started giving peeps a defining characteristic or hobby. For example, a child might be encouraged to be wild and destructive, while siblings are encouraged to be studious and quiet.

But generally I just let them do whatever, even if they choose to use this freedom to draw all over the walls.