How does one go about selecting a team to call one's favourite?

I suspect that those involved with sports journalism have already strip-mined this simple question of all its sentimentality and meaning, but ignorant of their theories, I will suggest that most sports fans pick up their fanatism from others as if exposed to something akin to chickenpox (generally a childhood disease... it inflicts only once... no major harm comes of it)

David Winner, a journalist, became a fan of all things Dutch early on, encouraged by the family au pair, Hanny, who explained that Holland is a country below sea level, planted all over with tulips and walled by dikes. When they need more land, they do not go to war and take somebody else's but extend their dikes farther into the North Sea.

The above except is from a book review in the July 2002 issue of Harper's Magazine. David Winner became a fan of Amsterdam's Ajax football club and grew up to write Brilliant Orange: The Neurotic Genius of Dutch Soccer. Here's more:

Amsterdam's Ajax football club (named for the bathtub cleaner, not the Homeric hero) undertook to play soccer as an intellectual exercise in strategy and grace. Winning, they said, is vulgar. They sent their fans into ecstasies -- a game Spinoza might play. They then thought up Total Football: every player taking all positions and with everybody as the captain.... They wore bright orange shorts and jerseys, and their unofficial club ensign was the Star of David. None of them at this time was Jewish. Their clubhouse was in the old Jewish quarter, which had suffered terribly under the Nazis. These emblems on blond, blue-eyed Calvinists had the added effect of discomfititing German teams and infuriating British skinheads.... They've had three sets of twins, for the fun of it, and they hugged and kissed on the field until a stuffy Sports Association made them quit.

I think I have found my new favourite team.