Hmm...how did I become a Cubs fan?
I was born in Chicago, but moved to Baltimore when I was 4 when my parents split. I considered myself a fan of the Orioles, Cubs, White Sox and according to my little league baseball card that asked my favorite team, the Pirates (this was 1991-1992 time frame when they were good).
I moved back to Chicago at around 10 (1993ish), and quickly dropped the Orioles and Pirates (though I've always had an affinity for the Orioles, though wouldn't consider myself even the slightest bit of a fan). It was then Cubs and White Sox. And I have to admit that while I liked both teams, I was more of a White Sox fan with those enjoyable early-to-mid 90s teams that were good but never really did anything. Frank Thomas was easily my favorite player of my childhood.
Now its 1998 and I'm still fans of both but have moved more towards the Cubs side even before the season started. 1998 was freaking magical and I was captivated by Kerry, Sammy, even Terry Mulholland and Mickey Morandini. Now I was like 75% Cubs, 25% White Sox. I watched the Sox 2000 playoff run but was much more detached. It wasn't until 2003 when I firmly committed to a side and fully turned my back on the White Sox. Since then its been all Cubs as evidenced by my 86,000 posts on this site (once the board finishes indexing)