Why is it...

... that some people in the IT field seem to take one look at me and think "programmer"? This has happened to me twice now: when I started my classes in Computer Networking and Security, on the first day my teacher took one look at me and announced to the class that here we have a programmer. Now, today, I'm in a job interview and I get told that I remind the interviewer very strongly of a friend of his who is a progammer, both physically and in general manner.

Don't get me wrong, I am very interested in programming... I'm planning on focusing more of my efforts in that direction over time. I just don't understand this programmer "aura" I already seem to give off, considering that right now my programming skills are not particularly advanced. I would have thought such a thing would be developed with time and experience, and it's a bit disconcerting to give off that vibe as a newbie.