The gamer I am today is from a number of events.
My first exposure to gaming was watching my cousin play NES. He almost never let me play, though. I did get my own NES shortly after that for christmas when I was 3 or 4 years old. I got hooked into gaming from there. Luckily so did my mom, who would play my NES while I was at school. So since she also played, it was easier to convince my parents to get me new games and systems as they came out.
I still game on all consoles, but my first love is PC gaming. That started in 1996 when I got the original Tomb Raider for PC. Not sure why, but it caused me to fall in love with PC gaming.
Gaming then lead me into upgrading and eventually building my own gaming PC's, as well as keep up to date on related technologies.
I think the final big event that shaped the gamer I am today, started with the Sims. I got into the Sims Online beta, and bought the game when it came out in Dec. 2002. I had met a good number of people in that game, one of which introduced me to Star Wars Galaxies. From that, I became a huge fan of MMO's and ever since then have always had an active subscription to at least 1 MMO. Sometimes multiple MMO's.
And that is where I sit as a gamer today. I own all 3 current generation consoles, numerous older consoles, multiple handheld systems, and a gaming PC. I enjoy most types of games, but prefer MMO's and RPG's. Heh, and I never feel as if I have enough time to game anymore.
Edit: I also can't forget, I am not very fond of, or good at, socializing, and prefer to stay at home than go out. That is also a large contributing factor to the gamer I am today.