The psychologists call it “sibling rivalry.” I call it brothers and/or sisters hassling, and country kids seem to have abundant aggravation resources.
My brother and I, as I recall, argued about most everything, but especially the important stuff like which bait would work best when we were fishing or whose turn it was to milk the cow. One day he snuck around and changed the length of only one stirrup on my saddle.
I admit I gave as good as I got, though. Once I hid the BBs to his new BB gun for a couple of days. As for our arguments I now realize my motto those days was “never admit you’re wrong.”