Inbreeding is very possible with snakes, but not a point to be made in this particular discussion. As has already been said by numerous people (including myself) inbreeding is simply not a factor in this particular genetic disorder. By the by in your example you would still not breed offspring to parent or sibling to sibling unto oblivion, you would combine it with other genes to make new combos (outbreeding) therefore giving your "new morph" the genetic diversity needed to stop the slow descent into missing eyes and deformed jaws. Inbreeding does have an effect on every species of animal in existence, it's only a matter of how long until it becomes noticeable.