As a very young child, I never owned a radio control car for more than a year without disassembling it and trying to figure out how it works. It probably didn't help that my father was an electronics QA technician. I never figured it out; I always managed to break them beyond all possibility of repair. A huge number of toys that I owned ended up suffering from a destructive disassembly.
When I was eight years old someone got the great idea to introduce me to model kit making. I started with simple Snap-Tite cars, but within a year I had moved into more complex glue-together models. With this hobby (and actual instructions), I was able to build something without breaking something else. The one model kit I was never able to complete was the H.M.S. Bounty, after I broke one of the fragile plastic sails (and it still bugs me).
I first became interested in computers during the fourth grade. A friend of my family had purchased an Atari 400 with a cassette data reader. Like most kids, I was amazed by the games. Soon, I got curious about how it worked.
I have no idea the technical side of what he did, but he showed me the source-code for a game - it was a game where a chicken ran back and forth across the screen with a basket, trying to catch randomly falling eggs. For all I know, he could have shown me some code for anything, and just told me it was for the game, but to me, he had shown me something special. A peek at what was under the hood. Parts to disassemble.
I never got to explore that computer beyond a few sessions while I tried his patience. I was insatiably curious, and (probably because I was an only child) I thought of myself as anyone's equal. I wasn't exactly a typically well-behaved child that way. The excitement of "seeing" what was under the hood for that first time has been with me ever since.
Another hobby I picked up, sometime around 10 years old, was electronics. I got one of those 50-in-one electronics kits for Christmas. These things have a bunch of wires of different lengths, and a bunch of components mounted on cardboard, connected to springs. There are a bunch of little project ideas in a book with instructions, and the components are connected to eachother by bending a spring and putting the wire ends in between the coils.
My father (and sometimes his friends) would bring home the same, loose small electronic components that were on the electronics kit. I learned how to solder that year, and made little permanent copies of some of the kit projects.
My first exposure to UNIX was when I was 12. My mother occasionally worked late-overtime hours, and would sometimes log me into a UNIX green-screen terminal to play an "interactive fiction" game that was installed there. After some research, I'm pretty sure that the game was Planetfall. I never did figure out how to do anything useful in the game - as the grammar was - at once - too simple and too complex for me to fully grasp. Not that I didn't try, and enjoy trying. I was not allowed to play with the command line, as this was my mom's work account, and she didn't want to get into trouble.
While not directly about computers, during middle school, I took an elective that was called Business studies or something like that. There were introductions to a number of business machines (mostly older things that were already being phased out of actual businesses). However, most of the class was dedicated to touch typing. Every desk had a very old IBM Selectric typewriter with all of the letters on the keys completely blacked out. There was a blown up graph of the key layout at the front of the classroom. This class, learning how to type, is a very useful skill to this day. My mother even bought me a Smith Corona typewriter for home, which is probably why the skill stuck with me.
I didn't have direct access to any computer again until the summer before I started High School.