This is, of course, largely a matter of opinion. People can come up with different theories about the causes of the Holocaust and whether it was a “natural” aspect of civilization. My own view is that it was, to some degree, a natural potential consequence of civilization.
Civilizations develop largely through a process where they become less egalitarian and less tightly bound by ties of kinship. When a society is small, like a band or a tribe, it is very egalitarian. There are few distinctions between different classes or types of people. Part of this is because the people are almost all the same in many ways. As civilizations develop and grow, these things change. The societies get to be much bigger and more economically stratified. There are now rich and poor and middle classes. The people are no longer the same as one another. They are no longer related. They no longer come from the same places. They may not even be of the same race or religion. These factors, I would argue, helped make the Holocaust a natural potential consequence of the rise of civilization.
As civilization grows and becomes larger, some people naturally tend to see themselves as superior to other people. The society is no longer homogeneous, so there is room to feel superior to others. The Holocaust arose in part because ethnic “Aryans” came to feel superior to other people in their society. As civilization grows, it becomes less cohesive because it is no longer tied together by bonds of kinship. This makes leaders have to search for ways to unite and motivate their people. The Nazis chose to unite and motivate their people through ultranationalism and hatred of others.
What these things mean is that the Holocaust came about in “natural” ways that are connected to the growth of civilization. It came about because some people came to feel superior to others. It came about because leaders needed to find ways to maintain solidarity and cohesion in society. Therefore, the Holocaust was not, in my view, an aberration.