Near-sightedness has a genetic component, but it is also caused by focusing close to the face for extended periods of time during one's youth (your eyes stop growing when you're around 20-years-old), resulting in one's eyes having difficulty focusing outward (near-sightedness). As people on this website tend to be nerds, and nerds tend to read and use computers more than the general population, it is no surprise that many of us are blind as smurfing bats.