I would not say completely arbitrary. I would argue that some is “deserved” and yet we do carry all the sins of our fathers as well. It’s an awkward thing to say, but as the human race spread out of africa, there’s a difference in those who left and those who stayed, and when this occurred. Whether or not you call this conscious or a result of the past, there is always at least the illusion of free will.
That is not to say the balance is remotely fair, and there have been many atrocities “on all sides” but you can’t say that because it’s taboo. I didn’t say all sides were equally responsible. This is “one of those things” that people don’t seem to get. That we perceive fault as binary, as do we consider will. It’s always both, the only question is how much of one or the other. That paradigm should propagate up through all lines of division of our species and further up those which have preceded us.