Initiation of consanguineous marriages. In family with α+-thalassemia, shortage of marriageable candidates leads to cousin-cousin and "cousin"-outsider unions. With the likely distribution of α+-thalassemia alleles shown above, on an average, 20% more children in this consanguineous union will survive malaria than from a non-consanguineous union. Here, the excess deaths due to inbreeding = 0.7F, i.e., 4.4% .
Denic et al. Malaria Journal 2008 7:150 doi:10.1186/1475-2875-7-150