This is an interesting topic and I think it gets at the heart of some of the reason believers end up believers.
Of course, this may just be a stretch, but, as youth we're more impressionable, the world can at once be much more magical and much more frightening (Remember the first time you were lost? Or the moment you graduated high-school or were in college wondering what the hell you were doing or going to do?). And each of us gets a different take on life - a different "roll of the dice" so to speak. Some of us get mediocre, bad, or detrimental circumstances to be fostered in.
I feel that, perhaps, some people are more prone to believe because they saw hardship during a peak/pivotal time in their earlier (not necessarily childhood) development - and they felt the need to reach out to something for help "correcting" the things that were causing them grief - as a kid, how many of us knew how to go about solving our own problems? And there were probably people around them who were informing them what that "something" they could turn to was - God, for instance.
Taking myself as an example - I don't really feel I had such detriment. My home life was always good to great, my parents loving and understanding - the worst I had it was being bullied at school from time to time. So I feel I had the time to reason things out for myself, never felt the need to turn to anything external because I never felt I had the really big problems that needed solving for me. By the time I had those sorts of problems I had had enough time to learn how to deal with them myself, or who I could REALLY turn to within the sphere of my life and livelihood to help me solve them.