According to some studies you'd have a 20% chance of an offspring being myopic with one progenator, while with 2 progenators, the chances are more like 50%. Then it says that there is a stronger sibling-sibling heridity than parent child. That is if one of your siblings has glasses, there is a stronger heritibility that you would have glasses versus if your parents have glasses. It seems to me that myopia is a disaster in the animal kingdom and even with humans, you'd much more likely to get lost or killed in the woods during man's days, and it would have been a disaster for you if you had myopia during those times, and even in some parts of the world today, you may just not find your way back to "home base" because you can't read the signs. So if you're a progenator and the children that don't have eyeglasses, does that mean that they have "bad genes" somewhere in them that will arise later farther along? Or is it like in some parts of the world where myopia is an epidemic, something that was caused by many progenators, and the weight of the myopia just kept building, and it will take an equal weight of natural selection of many generations to clear the myopia out of those areas? Kind of like ridding an area of the plague or a deadly disease.