What does it mean to kill your father?

Many people should have heard of the so-called father's fate, that is, one's own eight characters are not good for his father, or his father is sick, or he dies young and short-lived. There are many such situations. Once upon a time, there was a man who had a bad father. Since his birth, his father has been ill all the year round and his health has gone from bad to worse. This situation is not only related to the father's own eight characters, but also the child's eight characters have more or less influence on parents. So sometimes it needs to be resolved, but some people treat it with disbelief.