Not believing in the face of facts

Sometime you have been put into a situation that even if it is the fact and it is presented to you as such you still don’t believe it. It is human nature to refuse to believe the facts what you have been taught all your life and then confronted by something which does not fit into your accepted beliefs. I am the same too and I would be really shocked if I have to change my certain long term beliefs regarding something which turns out to be different then what I have been made to believe. This question came to my mind when I read that the Boston Bombing suspects mother does not believe that there was any bombing done and all the blood was fake and her sons have been implicated in this terrorism, even after the remaining bombing suspect gave the details of the bombing that he and his brother did. As somebody said on the internet regarding this that he understands mother's love but come on, how much evidence you need it in order to believe it when the suspect is implicating himself in the action. And it is not just this one situation but I can count numerous times that the believe system of the people refuse to acknowledge the truth even if they see themselves. One of the examples is that some people deny the existence of the holocaust in which millions of Jews died in concentration camps. Another one is the Elvis Presley, the popular rock singer of yesteryears is alive and will died.