I explained the same thing in a previous post about politics and genes. We form our political beliefs based on genetic predispositions, and then we adhere to them emotionally without logical thought.
From today's article:
It is possible to override these biases, Dr. Westen said, "but you have to engage in ruthless self reflection, to say, 'All right, I know what I want to believe, but I have to be honest.' "
Some commenters have questioned the link between genes and political belief.
Besides reading the post I linked to above, I also urge you to read this post by the "Libertarian Man of Mystery" which is a truly excellent post explaining how the genes which cause guilt are the same genes which cause liberalism, and the post further explains why Jewish people feel the most guilty and therefore are the most liberal.