Given the fact that the mutations seen in all of the children, despite being from different families, are identical, it’s likely that there is some common ancestor that lineages haven’t yet uncovered. Amish communities are tight-knit and generally only intermarry with one another, so it wouldn’t be surprising. In fact, it’s not the first time that an Amish community has faced genetic challenges. As an isolated population, genetically speaking, the Amish have developed unusual health risks resulting from having a limited genetic pool. And to make matters worse, it’s not uncommon for Amish couples to be fairly closely related, resulting in some problems from inbreeding.