Some who aren't may probably be recognized by their current differences from their ancestry, immediate family, old neighborhood, school friends, etc. Recognizable differences could be living standards, lifestyle, religion, and/or politics. They might also be more receptive of different opinions and be flexible enough to reform their own opinions when facts dictate it.
Then, there are the others. Told who they are either through birth, environmental observation, education - including religious, or life circumstances. They refuse to allow their thought process to be confused by facts.
Who are you?