afrikaners are a southern african ethnic group descended from a very few dutch settlers first arriving in the seventeenth and eighteenth centuries. the small population size of the original settlers meant that the colony probably had reduced genetic variation as well as a non-random sample of the genes from the original dutch population. today, the afrikaner population has an unusually high frequency of the gene that causes huntington's disease, a disease that causes the progressive breakdown of nerve cells.
explain, using the principles of genetic inheritance, why huntington's disease is common among the afrikaners.
a) the only contact the afrikaners have is with members of their own community.
b) the original dutch colonists just happened to carry the gene for huntington's disease with unusually high frequency.
c) the allele for huntington's disease is dominant and there are no other alleles that can mask the effects of the disease.
d) there was little outside genetic input to their population from immigration so the gene pool stayed exactly the same over the years