The holocaust and my perplextion

Learning about a lot of the new information that has come out due to new info from east Germany etc, has reinforced an important point that is not well known. The holocaust was not the idea of a few madmen, it was the accumulation of smaller atrocities that snowballed. It was not a top-down decision by the few but incremental atrocities by the bottom. Why is this the most perplexing part? It is because it demonstrates that we are very adaptable, so much so that we can adapt to do atrocities. Humans have the ability to believe in something so much that it convinces them they are justified in committing atrocities. Worse still is that this means it will in all likelihood happen again. We must remember that we come from (genetically) the most innovated and effective killers. Which brings me the my seemingly odd reflection, I cannot judge the involved people's actions since I cannot say with any measure of confidence how I would have behaved. I must see a reflection of a potential part of myself in the perpetrators lest I underestimate my capacity for atrocity.