Causation or Correlation?

I was reading an urban fantasy by a newish author last night. In the text, there was a more-than-casual reference to Linux code. Laughing, I checked the author's bio. Sure enough, programming is this author's day job.

It sure seems that most spec fic writers are, to some extent, computer geeks. Not all DBA's and programmers, of course, though a serious chunk of us are. But...bloggers, gamers, online workshop/critique group addicts, etc. I mean, who doesn't know some basic HTML code?

I wonder why that is?