I grew up in Red Sox and Yankee country (Connecticut) with a Yankee fan as a father and two Red Sox-rooting grandfathers.
When I was 'coming of age' in a baseball sense, the Yankees weren't very good and Billy Martin had just been hired as the Detroit manager. Dad loved Martin from his days as a Yankee player and talked about him and Detroit all summer long - I became a life-long Tigers fan in the process.
Talk about unintended consequences!