Yes, it's an old, as in really old mutation that apparently turns off the ability to make brown eye pigment. And no, most of those people likely didn't try too hard in school. However, it was also the school's fault, if they were teaching the same garbage I was fed. We had an over-simplified version of science, with charts that had things like brown+brown = brown 4/4 times, brown+blue=brown 3 or 4/4 times, and on and on. Hey it was the 80's stupidity was in style. ;)