Parents who don't teach their children not to touch things that don't belong to them. I saw fb post this afternoon by a friend whose youngest child took a work badge/pen as well as an ereader, hid them and then wouldn't produce said items when asked. I wanted to comment so badly, but couldn't figure out how without sounding like a b*tch.
We taught our children not to touch/take things that didn't belong to them, especially badges, wallets, etc. It worked when it came to not touching my or my husband's belongings. Not so much with toys, etc...but that's part of being a child and not wanting to share.
*stepping off soapbox*