Have you every noticed everyone has what I call a Geek Button. That is the one subject that they are so Passionate about that once you get then started talking it is hard to get them to stop. Finding Someone's Geek Button Can be fun, with such Power comes great responsibility.
Not everybody's geek buttons are what society considers geeky. My Dad cannot stop when you start him on John Wayne or Clint Eastwood Westerns. I have a co-worker whose geek button is Pro-Wrestling. Also not all geeks are men. I know a few female X-Files Geeks, Neil Gaiman's Sandman geeks, Charmed and/or Buffy the Vampire Slayer Geeks. I know of a grown woman that was a Barbie geek. Have you ever seen a NASCAR nut geek out about Dale Junior, I have Scary. In Many ways Goths can be slightly geeky, ever seen Abby on NCIS (Fairly realistic). Plus you got closet geeks. People that you meet that you would not believe watch Doctor Who or Star Trek. Plus in today's Day and Age it seems like the Geeks are inheriting the earth.