I was always allowed to believe whatever I want. My parents weren't religious, though my father did go the Christian route a few years ago (well after their divorce). My tendency towards Atheism comes from a lack of proof. That and I tend to believe the Scientists have some idea about what they're talking about, and can throw some evidence my way.
Case in point.However the reasons that the majority of atheists have for not believing in them is that they can't see enough evidence of their existance. And because of that most atheists would not believe in an afterlife either.