It is difficult for people to understand that what is "proper" and "good" is a matter of cultural definition.
Most people everywhere have a tendency to regard their own cultural practices as the best ones, or the only ones that are moral or virtuous.
In so far as other cultures come close to their own, they are regarded as not being so bad.
But in so far as other cultures diverge from their own culture, these cultures are regarded as immoral.
This tendency, found everywhere in the world, although in especially high degree among certain people, is called ethnocentrism.
Americans, along with the French, the Arabs, the ancient Greeks, and the ancient Hebrews, and a few other peoples, have cultures which are particularly characterized by ethnocentrism.
Individuals who are most ethnocentric within any given culture are those whose experience has been narrow, whose ability to understand other people (even in their own group) is not great, or whose inner feelings of insecurity are so great that they are afraid of every deviation from the expected.
~ T. W. Adorno