Even though there a few differences, your story is pretty similar to mine.
I always got the impression that I was isolated from my colleagues, I was an uber perfectionist and feared making mistakes because I believed that I would be "happy" if there were no points to people tackle on, in spite of this being inherently quite stressful (it is the same as being paranoid, really) I've never got problems like depressions or something like that, mostly because I was always REALLY self-centered.
The family plays a really important when we are talking about being self-centered, mostly because your social environment can't me much different from this simple sum: family (your household) + school (your colleagues) + friends (hmmm, special colleagues most of the time, not only restricted to school though). And being self-centered, is the same as ignoring others, your family, your friends, other human beings in general and to do this, to put your self in a isolated position from other, is not an easy task.
Since I've always got the feeling of isolation, it probably is not surprising to say that I didn't have many friends and even if there were people who someone else might call friends, at this point I have never opened myself to anyone, my world was basically my head, me with myself and my physical world was school+my house and sometimes other places where I focused on practiced sports, etc...
In this situation, my father (I've got no mom, though I got an step-mother and an aunt, who are something like a mother to me...), my family and I have always had a tacit agreement: I would be responsible for my actions, I would have no problems at school, thus I deserved "freedom"; and things proceeded like that, they always had.
I remember that before I was five I was really egotistical, possessive, misbehaved child.
The father figure is interesting at this point, because even though he never spanked really badly, he only disciplined me and put in me some common society's values, I was really afraid of him, of his rash voice, I feared my weak condition (I always fear weakness, my weakness) whenever I faced him.
This fear, was probably one of the main reasons to avoid conflict, to resignate, to shut myself in my thoughts, to become analytical and being able to do things people wanted me to, so they would be pleased with me and leave me alone.
Under this conditions it is not surprising that I developed my logic, my rethoric and my observing nature of my surroundings, all of these were tools that I used and abused for long years, to maintain my condition of "freedom".
I dunno if I succeeded in being impartial... Anyway, looking from far way this (my life) might look something dull and boring (without human contact and all), but I was quite happy actually: I got no problems and I could spend my free time doing things I like which were mostly playing games and that is good! Games are entertaining products made because there are people who are willingly to spend time with them.
I didn't see it before, this article has some pretty accurate stuff O.O
(...) whizzing through the most challenging video games(...)
INTPs are also at home with a computer's many creative possibilities and the unlimited opportunities to dabble with and explore whatever piques their interests. Given their high need for time alone and their penchant for 'noodling' things around inside their heads, it's no wonder that most or all of the favorite activities of INTPs are fairly intellectual and usually pretty solitary and internal.
Well this was mostly my middle school life, before I was nothing more than a curious child who was disappointed with the world, with the adults, because people didn't care to answer my questions, so, as you can see, I resigned myself and shut the doors to the outside world.
("Ah... There is nothing worth out there.")
That conception started to change in highschool, I started to to wonder about people, about the others, and the most important thing was that I started to wonder about my life trajectory. It may be a thing from teenagers, but I gotta a need for challenges, to struggle for higher things (at least in theory), I was somewhat bored with how familiar, how unchanging things were, so I decided to try to chance.
And here I am now, this past year I changed a lot I am trying to open myself to some people, I convinced myself to believe that there were interesting people out there, in fact a great deal of people were interesting, but they put a facade that was not, I convinced myself that I was "deceived", that a was naive, thus it was time for a change, time to open my eyes.
Easier to say, than it is to do, but the challenge is there and it quite cool to meet, for example, some INTPs in my own classroom.