Question

The Pennsylvania Dutch Amish have historically been a small, isolated population in the United States. Within this population, there is a different frequency of alleles than there is throughout the population of southern Germany and Switzerland from which they came. Given this information, how is it possible that polydactyly, or the condition where people have extra fingers and toes, is more common within this group?

Answer 1

Amish groups in general are close and do not socialize with foreign groups.

Step-by-step explanation:

This means that many times, Amish tend to form families inside their own small communities. This may mean marriages between cousins or other close family members.

In this particular case of the Pennsylvania Dutch Amish with cases of polydactyly may be the result of children being born from parents being members of the same family, the result is this mutation called "polydactyly".

Other southern Germany and Switzerland groups, not being Amish and being more open to socialize with different groups, reduces the percentage of polydactyly because marriages between close-family members are not so common.