Is it natural for a person to laugh when two adults are screaming at each other in the next room?

Let’s start off with my age. I am currently thirteen as of February 2. I live in a house with seven people including: my three cousins (ages 3,5,6) my brother, my mother, my uncle, and my dad. My uncle’s ex-wife got back together with him as of late. His ex-wife isn’t the best person to be with. She is very bossy and acts like she is the law of the land. She’s always screaming at my cousins because they forget to do this… or they hesitate for a second… or SOMETHING. It’s very annoying. She yells at my uncle for not doing as she says.
My uncle was doing the laundry today and asked her a simple question: “Which ones are school clothes?”
She went on a whole rant on how he doesn’t ‘participate’ in the house and blah blah blah. He screamed at her saying “I AM NOT YOUR SLAVE!!!” she started throwing his stuff out of the house because he was walking away. He started screaming at her again saying that he thought they agreed if they ever got in another argument, they should just walk away. He was doing just that, and she was screaming at him for it. It escalated from there, but there were no fists thrown or anything like that, my uncle has self control, mind you.
I was laughing in my room the whole time. Siding with my uncle on this. He went on a whole rant on how their definitions of ‘participation’ were obviously different. I found it amusing, and I’m wondering why.
Any answers will help in my lifelong quest for knowledge.
-BBawlight