Health Among The Amish

"Health among the Amish is characterized by higher incidences of particular genetic disorders, especially among the Old Order Amish. These disorders include dwarfism,[1] Angelman syndrome,[2] and various metabolic disorders, such as Tay-Sachs disease,[3] as well as an unusual distribution of blood types.[4]" (Wikipedia)

Any cult/closed community may have a high risk of genetic disorders but also may have some positive social traits.  Click on this link for more.