Here's an article suggesting that people's political orientation depends on how their brain is structured. On the one had, it suggests a logical reason for our political differences. At the same time, who doubts that this information could be used--by either side--as an efficient, "logical" way of identifying and eliminating political opponents.
Don't think that this issue is only a problem in totalitarian or authoritarian societies. The answer to the question "Can it happen here?" is always yes.