What makes one a runner?

So I've now been running 3 times a week for a little over 3 miles a run for about a month. I've found this gel stuff that I swallow down before a run and it helps with the body and fatigue throughout the run, so I am doing the 3 miles without a problem. Yet I wouldn't classify myself a runner. I want to run a marathon in October, but I still don't think I'm a runner. What makes someone a runner? I guess liking all that running makes someone a runner :)