We know that unconscious bias happens in all of us. We categorize, we find patterns, and we like to group people. We decide who is in our “in group” – and then we favor our group. This ability to tell who is a friend, and who is a foe, helped early humans survive.
We like to think we are all reasonable open-minded humans who do not pre-judge other others, but much of bias happens hidden away from our conscious decisions. We all have bias. Our unconscious mind is wrong, often, especially on matters that truly would benefit from thinking rationally.