I do not think prejudice is a "learned" mechanism, though it is a mechanism,I think humans have to learn not to to be prejudiced, because being prejudiced against strangers, has been an advantage in reproduction way too long. I highly doubt sociology, in my eyes the most useless academic field and I am a strong believer in in social biology, genetics and evolutinary behaviour sciences, I have been studying social sciences way too long, being confronted with Freudianers and "Your peer group forms you, you are nothing" sociologists.