"I do not know which makes a man more conservative — to know nothing but the present, or nothing but the past."
-- John Maynard Keynes
My experience suggests it is a knowledge of the present in the absence of a knowledge of the past that is the key factor. The history taught in school is at best superficial and at worst distorted. Knowledge of the past filtered through the rosy glow of contemporary high school history texts warps opinions. My friends who are most conservative seem to have the least real knowledge of the past ... though, in their opinion, their knowledge in that area is superior. After all, they tested well in high school history.
As a demonstration, if you think you know something about history, give "Lies My Teacher Told Me" by James W. Loewen (Touchstone) a read. (1, 2, 3) The title may be a little off putting (I found it so*) but the content is what counts. The book represents a critical analysis of 12 American history text books used commonly across the United States in the teaching of high school history - a survey of their strengths (there are few) and their weaknesses (there are many).
Which brings us to a lovely quote from Winston Churchill:
"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing ever happened."
* The title implies that teachers are liars. I don't believe it. Here's why. If a teacher is taught from a text book that doesn't have the story straight, then goes on to teach the text book, the teacher may not be teaching the truth ... but it is not the teacher who is the liar.