Well, good question...

Hated, (in the sports sense, obviously), came about... for me... gradually. The first team I 'hated' was the Colts, division rivalry... but it was an entirely different type of 'hate' than the 'hate' I have for Seattle and the Niners today... it was more 'respectful' in nature... a "worthy foe" so to speak. (yes, I've regressed emotionally )

Green Bay close behind the Colts... nearly the same time. And like you into the 70's the Vikes took the lead. For some reason I never developed a real hatred, (again, sports hatred), for the Cowboys... certainly didn't like them, then or now... but that was a much lower level of 'hatred' than I had held for the Colts and the Packers and a HUMONGOUS step down for my distaste of the Vikes.

Today it's Seattle and the Niners, obviously... although I've never liked the Falcons... but for no good reason. Just something about the Falcons pisses me off.

Interesting, to me anyway, and nearly sacrilege on this board... my 'hate' for the Niners is mostly vicarious. Following other fan's hatred. But don't misunderstand... I truly detest them. I've said this many times on this board but since I've been a Ram fan the number of truly 'meaningful' games between the Rams and Niners are incredibly few. Other than some what I consider extraneous and/or 'invented' reasoning hate, (still absolutely legitimate however) like the Niners win streak or 'geography' there just hasn't been enough meaningful game, especially for a division opponent, for me to take that next step to a hatred on par with my hate for the Vikes. That is changing here recently, and rapidly. - JamesJM