One of the most basic questions in Argentina is ¿De quien sos?, who are you from? It's a football question. In most contexts, few here will think you are asking about their parental or nationalist history, though both are deeply intertwined with football. I've tended to follow this question with a second, ¿Porque?, why?
I'm starting to realize that this might be the wrong question, or one without a very good answer. The typical response is because someone in my family, usually the father, is from the same club. I've been told that the feeling one has for your team is something inexplicable, like love. You can have 'reasons' but these do not explain why you have such a deep feeling. At least there is no systematic way to categorize how someone becomes a supporter of a team. It is something you carry with you 'in your blood', for some it is their blood. I've heard a San Lorenzo supporter defend their fanaticism by pointing out, "what colours are your blood? You have blue blood and red blood, just like San Lorenzo."
For a Canadian football ('soccer') fan, fairly removed despite the internet and television, from most of the major footballing cultures it is hard to participate in the cultural processes that make the deeply emotional experiences that many supporters feel. For a long time, small bars hosting Saturday morning Premier league games served as the small enclaves of social interaction that I'd argue is an important part of the emotional development of a supporter. Football culture is starting to open up in Canada, however, and has gone 'public' with the re-invention of professional soccer in Toronto, Vancouver, Edmonton and now Montreal. Previous street celebrations in ethnic neighbourhoods during World Cups and Euro Cups have also played a big part. Hopefully the national teams will also play a bigger role in the coming years.
Nevertheless, soccer is not broadly embedded into the social culture. In Canada, Who you are from? is a question about your ancestors. And if you encounter a soccer supporter who has a team in Canada, their response to my second question "why?" is a rational question that you respond to with reasons. Recently, on the Footy Blog journalist Richard Whittall provided a "Guide on How to Pick a Football Club", advising you on the criteria that you can use to 'pick' a European team. Whittall suggests you can pick a team based on a moment of glory, results, team history, or personal ancestry; and support local (don't be a snob!).
It is an interesting example of how 'relevant' soccer is becoming in Canada, that people are interested in having 'my team' and reasons 'why'. The comments are interesting; a mixture trying to fit into the categories given, while a few are sublimely unreasonable: Adam @ 4/5/12 3:31pm writes "Gunner till I die!!!!!!!!!" or Johnny @ 4/8/12 3:34am, who writes: