[user104658]

No, because the idea that parents have FULL control over their children's behaviour at ALL times is a complete, and dangerous, illusion. Just because they're kids doesn't mean they're not individuals with free will.

A kid being a (serious) bully can often be an indication of troubles at home. I would add to that that "serious" is important here; the uncomfortable truth is that almost all children will engage in mild non-physical bullying at some point. It is also not ALWAYS an indication that anything is wrong at home.

A kid who is a known bully continuing to bully does not always mean that the parents are unaware or aren't actively trying to do something about it. There's no surefire way to get it to stop. Parents and schools can be doing their best, working together, and still have a child with troublesome behaviour. Frankly... for most it's a phase that most just grow out of. I know that isn't much comfort for those who are being bullied, but it is what it is... and often the best solution to a serious one-on-one (or several-on-one) bullying situation is simply to try to ensure that the opportunity doesn't arise / those kids aren't together unsupervised.

In short it's a ridiculous idea that assumes kids are robots and that if you "do the right stuff" they will be perfect. It's just not the case. By all means take a look at the parents, but if they're genuinely concerned and engaged in trying to sort it out then that's really all there is to it. If they don't seem to care / aren't bothered about finding a solution / are actively doing something that's causing their child to lash out, that's another story, but honestly those cases are nowhere near the majority. Most parents are horrified when they find out their kid is bullying, and even more horrified when they can't figure out why, or how to convince them to stop.