I agree with how long someone lives there is probably the main reason but I have friends who adopted their dads team and never actually lived in the home state of their favorite team, this has always kinda baffled me. I moved from Illinois in HS but held onto the Bears until mid twenties. It seemed kinda silly for me attending every Bucs game and them not being my favorite so I trashed by Bears, Blackhawks and Sox gear and became a homer, moved again and after a few years did the same. Not sure how this plays out if I move from Texas.