What kind of argument between an uncle and his nephew could be the reason why the nephew no longer wants to speak to the uncle?

The nephew is a follower of the Left Party and notes that the Uncle is a member of the AFD.

Rumorly, the nephew hears that his uncle should have sexually abused him as a little boy. Another rumour: The friend of the nephew has disappeared for years. Some people say that the uncle knows more, but for good reason he doesn’t want to say anything. The nephew doesn’t think. For him, the uncle is a perpetrator.

So rumors, mutations that he should have done something bad to the uncle to whom the nephew is connected.

Or otherwise: The uncle has the nephew. to the police because of an act that he did not commit. The only point that the uncle has is the long hair of the nephew. (This makes him suspect in the eyes of Uncles. But the act as such has actually committed someone.)

The uncle is a mathematics teacher at a gymnasium. The nephew’s girlfriend was his student. Because of poor grades in mathematics and some other main subjects, she has to leave school. The girl reports to her friend, the uncle finished her in front of the whole class during an oral examination, putting her particularly difficult tasks. During the class work he fixed them constantly and insecure them that they could not concentrate. The case with oral examination before the table was not only once. She was constantly tested orally, sometimes three times a week. (Maybe that’s true or maybe the girlfriend is lying.)