The Tennesee fandom comes from having father's side of the family being based in the Morristown/Johnson City, Tennessee area, about 45 minutes outside of Knoxville. He kinda programmed me to be a Vol fan, since I've lived in Charleston all my life.
The Green Bay fandom was a completely objective decision made on my part when I was 12 and decided to start watching football. I wanted a team that was known for the insanity of its fans, had a lot of history, a simple easy-to-draw logo, and was generally good. If I had gone with my father on the NFL team to like, I'd be a Jets fan. There you go.