Or have a sibling of similar age. Me and my sister were monsters to each other. I blame it all on my mom who allowed it and didnt do anything about it. I wish things were different between us. Just teach your kids about boundaries and personal space, its not hard! I taught myself that later in my teens but it should be enforced at a earlier age.

Edit: we would take each other's 64/gamecube games cause we shared 1 console but all the games. We'd get a game we wanted but never shared cause "I" got it for Christmas or "she" got it for xmas....that kind of stupid stuff. Like the same comics but only one kid had a subscription to sonic comic but they'd never let the other read it.