Unfortunately, we don't KNOW what the norm is for a situation in which one man excercises absolute and total control over a group and there is no one to gainsay him. The closest comparisons I can thing of are the Jonestown suicides and the Waco deaths.
Children of the sect born with fumarase deficiency disease may have died in relatively large numbers. The disease can be severe, or mild, the victims sometimes die early, sometimes later. I would wonder how many died from this genetic disease at that location. Even newborns can be severely affected; or it may not do its damage until the child is older. As far as I know, there is no treatment and it is always fatal, plus it causes severe retardation.
So, who knows?