They recently did a study that proves that winning at team game types like ONS in UT 2K4 pumps you up with testosterone but playing DM vs. friends makes 'em shrink. That explains why I don't like DM that much... not sure what it means for guys that do like DM. Here's a summary:

http://arstechnica.com/science/news/2010/04/unreal-hormones-males-treat-...

I always wondered why guys have the tendency to form clans... it is carnal instinct.