I have a confession and a question

I am addicted to Magic: The Gathering (known to those of us in the know as M:TG) a collectable card game and some how Google Reader knows this! It recommended this site to me. The only way someone would know about me and M:TG is by my emails as get emails about it and my delicious account where there is a number of links to M:TG. None of the blogs I read mention M:TG so am totally perplexed! So my question is how does Google Reader know I like M:TG? Is it looking in my emails for ideas???? hmmm dodgy!