Jerome Kagan believes that we live in a dynamic system where humans always adapt and change according to surroundings.
This is a good interview in which Kagan explains some of the social development of the human brain.
For me, it proves that if one is exposed to truth but chooses to retain unsound beliefs, it is not because they are brainwashed. It has to be more of a psychological preference, fear of self control or fear of being wrong even though good research says outherwise.
The inteview is quite long. But I think you will find Kagan very informative.