Weird phenomenon occurring in family conflict?

You can not control other people. Not you uncle's behavior nor the rest of your families seemingly inexplicable behavior. What you can do is figure out your best course of action given the situation you are in. You can voice reason at appropriate times but I recommend avoiding conflict [physical altercations]. Often in my own life when I find my self getting too wrapped up in family dynamics, I foresee might happen, I ask myself what I want at the reunion or holiday? What do I hope to gain by going? Often that clarifies the situation and makes the goal attainable. I want to be happy and see everyone have a good time certainly not argue & scream, It helps me sidestep getting into a spat that can arguably have a very predictable outcome. But ever family is different and some houses I would never enter. Discounting of personal experience is rampant.