But the majority did those horrible things..majorities of those who were in power.
We're not talking about majorities when we're talking about us, but individuals, however, if you're referring to all of us living in richer countries, then yes, most would likely do these things, but you can't really generalize like so, because there are almost always exceptions. Generalisations only take you that far.
I just see things like this: Most of us are similar in the way that we could and would do horrible things, for our own amusement or whatnot. Especially during wars there is lesser restrictions on actions and feelings in general, it's murder anyways.
The most horrifying thing in my opinion, though, is that we justify these horrible things with ideas and concepts, and at other times there's no justification at all, not that such things could ever be justified.
I remember reading about interrogations of some Nazis about why they did what they did, and they answered it with 'we don't know, we just did what everyone else was doing', so I'm thinking it's a bit about not wanting to be left out, which is weakness, since we're alone anyway.
I can say that I would not do anything like that directly, I'd find a way out of it, definitely. But I know that with the way I'm living, the way society is constructed, that I'm indirectly harming others.
Lastly, I wouldn't ever say that anyone is the same as another, only ever that they would share similarities, even between twins, as they ultimately are different entities and won't experience the exact same things. So, I will stand firm in my saying that everyone isn't the same.