I don't remember any sudden move towards rationality - I was raised in a godless household in a mostly godless country (France). I've always been pretty interested in science-fiction and in religion (though not as something I might believe in).

What pushed me a bit more towards rationalism:

• Maths classes that required a lot of demonstrations (and having to be able to do them again on the blackboard with an examinator)

• A physics teacher who insisted that we always include an uncertainty factor throughout our calculations, and not give excess decimals (I've noticed that I tend to think in terms of probability distributions more than others around me)

• Questioning a lot of my political opinions, and noticing when my brain was "up to no good", for example when EvaluateAsLeftWingOrRightWing(idea) was being called before EvaluateTruth(idea).

• Getting annoyed with atheists who consider religion to be the only domain where one can be irrational

• Working as a programmer, which doesn't leave much place for wishful thinking

• Reading Overcoming Bias daily