It's folly to think that you are free of prejudice with the only basis that you don't consciously hold these prejudices, because we (humanity, science) know for a fact that biases are much more deeply ingrained in most of us.

This is particularly hard for our demographic (programmers et al) to hear, because we consider ourselves rational. We like to think that we do things because we have thought them through. But all evidence points to the fact that we are just as susceptible to biases and prejudice as everyone else. Indeed, nobody seems to be free of it, but there is a silver lining: with an analytical approach, it is possible to examine biases and become aware of them, and eventually work through them.