I agree with all of that, but possibly in another direction.

People are nuts and so will unite against those that are different and make fun of them. It likely did happen to the cousin multiple times with other kids and when the brothers seem to do it as well, the uncle lost faith in his extended family.

The situation itself might have been imaginary, but it’s most likely an imagination drafted from past experiences.

People suck at times, even ourselves. We should come to terms with that and try to minimize the number of occurrences.