I found this source on genres. The site has quite a lot of critical analysis of what a genre really is and how as a society we separate and identify different genres. It seems that we tend to often associate things with each other and categorize into general groups. I found some interesting research here that tries to analyze whether the separation of different genres is learned or something we are all born with.
Chandler, Daniel. Aber.ac/uk. An Introduction to Genre Theory. 04/10/2000. University of Whales. 04/20/06.