Why does Shakespeare not tell us what started the family feud? Answer in complete sentences.

In the play it does not mention what the feud is about or how it started. It is thought that the feud has been going on for such a long time that even the families don't remember what it was about. Despite this, the ladies and lords of both houses are too stubborn to stop the feud from continuing, and even the servants hate each other because the families do.