Group 1 will never be programmers, group 2 is where I fell the first time I tried it. Group 3 probably have some training and group 4 probably have some programming related experience, or maybe they are superheroes. At any rate, anyone in groups 2-4 can become excellent programmers if they apply themselves and get the help they need. They can be plotted on a programmer competency bell-curve. Group 1 are the people who will never learn to code because they refuse to try. They probably make up the first hump of the perceived bi-modal competency graph. But they were never really in the running at all.

I can think of at least 2 people in my 30-person cohort in college who did not know how to code, and would fall in the first hump of a bi-modal competency graph, despite having passed 2 years of programming courses.

So my theory is that the second hump is a normal bell curve, and the first hump is people who won't try.