To break up the awkward silence at the start of a recent Overcoming Bias meetup, I asked everyone present to tell their rationalist origin story - a key event or fact that played a role in their first beginning to aspire to rationality. This worked surprisingly well (and I would recommend it for future meetups).
I think I've already told enough of my own origin story on Overcoming Bias: how I was digging in my parents' yard as a kid and found a tarnished silver amulet inscribed with Bayes's Theorem, and how I wore it to bed that night and dreamed of a woman in white, holding an ancient leather-bound book called Judgment Under Uncertainty: Heuristics and Biases (eds. D. Kahneman, P. Slovic, and A. Tversky, 1982)... but there's no need to go into that again.
So, seriously... how did you originally go down that road?
Added: For some odd reason, many of the commenters here seem to have had a single experience in common - namely, at some point, encountering Overcoming Bias... But I'm especially interested in what it takes to get the transition started - crossing the first divide. This would be very valuable knowledge if it can be generalized. If that did happen at OB, please try to specify what was the crucial "Aha!" insight (down to the specific post if possible).
It was happening slowly while I was growing up. I can remember many small times when I was breaking away from tradition and the beliefs of my parents and family. Things started to speed when I discovered OB and Eliezer... Then I started university.. A very rigorous course in maths emphasizing the axiomatic approach to maths. A very logical course in physics. Then I started reading the quantum physics sequence, something I had not done before. I read No Safe Defense, Not Even Science (http://www.overcomingbias.com/2008/05/no-defenses.html) and that was the crucial "Aha!" point that pushed me over the edge. This was only a few months back. And here I am.