What is a Coefficient of Inbreeding?
A coefficient of inbreeding is a measure of how much homozygosity we expect as a consequence of inbreeding. Genes are said to be heterozygous when an individual has two dissimilar genes for a trait; when the two genes are the same, the individual is homozygous for that trait (or that gene pair). We don’t have the technology to measure the actual gene combinations, but we can calculate the probability the genes will be the same by looking at the pedigree. Each parent contributes 50% of their genes to their offspring. Thus, half-siblings like Ram B and Ewe C in the example below have 50% of their genes in common with Ram D, since they are both fathered by Ram D. But Ram B and Ewe C may have from 0 to 50% of their genes in common with each other – that is, of the 50% of the Ram D genes that Ram B received, somewhere between all or none of those genes may have also been sent on the his half-sibling Ewe C. On average, they will have received the same genes from Ram D half the time – so they
