(Not particularly rationalist here, but.] In my case, it was a series of unpleasant things over which I had no control. When we were about 6, our parents had to send my sister and I to live with grandparents (due to financial uncertainty.) We mostly liked it there, though gr.-p. often had loud quarrels (to this day I hate shouting most of all. It helped, when puberty ended, to argue calmly.) Yet I had a recurrent thought - what will happen when our grandparents die? And I was revolted with myself so much I flat out decided not to think it; but later, when we were shipped back to our parents and it became safe to think again, I returned to it. I know what a resolution to omit something in my head feels like.
We returned to our parents at the adult age of 12, into a different country with a different language (Ukrainian) taught in schools, a different moral in history lessons, different everything. We had each other, and a raging case of Us vs. Them. It took years to admit to myself that maybe I don't have to completely break the way I think to fit in, mostly because we changed schools and were blessed with having an extraordinary biology teacher. (It was then that I learned the value of belonging to a group with common interests, and it shaped my life choices afterwards.) Our father is a physicist, and very pedantic in speech, which we tried to follow as a model. It didn't endear us to our classmates, which gradually showed us the weaknesses of being untimely pedantic. ...in college, I had a hothead friend who passed judgement on people quickly and forever. I vaguely understood he was wrong in this; and was at once assigned his 'conscience', for a short while. It made me willing to at least hear the other party out. ...I realize this sounds like a cliché, but being an atheist among Christians was useful, too. I had many opportunities to not let the argument be swayed into religious disagreements, or to leave when it was beyond me.
I'm reading Dan Ariely's book Predictably Irrational. The story of what got him interested in rationality and human biases goes something like this.
He was the victim of a really bad accident, and had terrible burns covering ~70% of his body. The experience was incredibly painful, and so was the treatment. For treatment, he'd have to bathe in some sort of disinfectant, and then have bandages ripped off his exposed flesh afterwards, which was extremely painful for him.
The nurses believed that ripping it off quickly would produce the least amount of pain for the patient. They thought the short and intense bursts of pain were less (in aggregate) than the less intense but longer periods of pain that a slower removal of the bandages would produce. However, Dan disagreed about what would produce the least amount of pain for patients. He thought that a slower removal would be better. Eventually, he found some scientific research that supported/proved his theory to be correct.
But he was confused. These nurses were smart people and had a ton of experience giving burn victims baths - shouldn't they have figured out by now what approaches best minimize patient pain? He knew their failure wasn't due to a lack of intelligence, and that it wasn't due to a lack of sympathy. He ultimately concluded that the failure was due to inherent human biases. He then became incredibly interested in this and went on to do a bunch of fantastic research in the area.
In my experience, the overwhelming majority of people are uninterested in rationality, and a lot of them are even put off by it. So I'm curious about how members of this incredibly small minority of the population became who they are.
Part of me thinks that extreme outputs are the result of extreme inputs. Like how Dan's extreme passion for his work has (seemingly) originated from his extreme experiences with pain. With this rule-of-thumb in mind, when I see someone who possesses some extreme character trait, I expect there to be some sort of extreme story or experience behind it.
But another part of me thinks that this doesn't really apply to rationality. I don't have much data, but from the limited experience I've had getting to know people in this community, "I've just always thought this way" seems common, and "extreme experiences that motivated rational thinking" seems rare.
Anyway, I'm interested in hearing people's "rationalist backstories". Personally, I'm interested in reading really long and detailed backstories, but am also interested in reading "just a few paragraphs". I'm also eager to hear people's thoughts on my "extreme input/output" theory.