The whole idea with the hooks is that it's a sign that the animal is het for something. Keep in mind that a co-dom morph IS a het. The super form is homozygous. In this case, a lesser is the heterozygous form of the BEL. As for het hypo's being lighter colored snakes, this could just be coming from selective breeding. The idea would be to use light-colored hets to produce hypo's that are brighter and don't darken up as much with age. Which in turn would end up producing more light colored hets when bred.