Do parents know when their kids are being jerks in the outside world?

I'm new to parenting having become guardian to my 10 year old nephew one year ago. No kids of my own. This has been a year of jaw-dropping realizations. My little guy is a good kid with good manners & a can-do attitude, but I would want to know if he was being a jerk to other kids or in school or public settings, and I'd make it a priority to fix that, pronto. He has at least one friend who is often a jerk to other kids and has displayed that behavior in front of me, he has also just finished a summer day camp and I've been hearing about kids crying and throwing tantrums after losing games, as well as cheating every chance they got. Do parents know that their kids do this stuff? I know that the parents who had to be called in because their kids were having meltdowns know, but do they care? Do they make excuses? Do they work with the kids on their behavior? I am just really curious and amazed. via /r/Parenting http://ift.tt/2alFTIg