Please understand that no geese are mean. It's their nature to attack anything that makes them nervous - and since geese are prey, a lot of things can make them nervous. Geese have survived in the wild by being born with acute instincts for what might be dangerous. A gosling that has never met other geese will still scan the sky for potential predators. They're born with the best survival instincts!
Those instincts make goslings the cutest pets: always following you, no questions asked. They rely on you as their parent to fend off potential dangers. But those instincts also make grown geese a bit of a challenge. They'll hiss, charge, bite and slap if they get too nervous around you. And they'll remember the slightest "injustice" for ages. Geese are not great thinkers. If they're scared by something while you're around wearing a bright orange hat, they may deduce that you and the hat are the origin of the threat and treat you accordingly.
If you want to raise geese succesfully, you have to teach your kids how to behave around the geese; not the other way round. No sudden movements, especially while the goslings are young. No teasing, no running around, no yelling, no flailing. Greet the geese in the proper goose manner: bowing, nodding and talking while slowly walking towards them. Never chase them, let them come to you. Spend lots of time with them so they get used to your company.
Or just keep kids and geese totally separated at all times.