There are frequent references to marriages between close biological relatives in the Bible, for example, the Patriarch Abraham and his wife Sarah (Genesis 20:12), and Amran and Jochebed, the parents of Aaron and Moses, who were related as nephew and aunt (Exodus 6:20). In both cases the parental couple would be expected to have inherited identical genes from a common ancestor(s) at 25% of all loci and so, on average, their offspring would have been homozygous at 12.5% of loci, equivalent to a coefficient of inbreeding (F) of 0.125.