Nothing is more irritating than people who look at you like you’re stupid. Sure enough, if the Mom’s a bitch (one common scenario) or something similar (the Dad is an obnoxious loudmouth), the kid comes out as a bully,
This might not always be the case though. It seems like one group of rotten kids I saw had fairly normal parents. However, I think the parents were naive, as they never paid attention to their kids, so the kids did their bullying when Dad/Mom wasn’t looking!
Kids have to be raised right by the right parents. Some kids are actually good cause of this but, as expected, they’re are tons of bad kids also.