There seem to be no correlation between type of parents and child, not like eye color is past in generations. The type seem to be totally random from all we know today. So each person have hundreds of generations in their DNA and so there have to be at least a few of each type in each "line" of offsprings. Maybe someone with a lot of some type inherent a body more fit for it due to evolution. So if in many generations a persons parents and parents-parents and parents-parents-parents and so on have been SLE the actual body is developed to fit the SLE but if this last person turn out as EII it might be a hard life. Thoughts?