Coefficient of inbreeding

The coefficient of inbreeding of an individual is the probability that two alleles at any locus in an individual are identical by descent from the common ancestor(s) of the two parents.
The coefficient of inbreeding is: The probability that two alleles at a given locus are identical by descent.
The coefficient of relationship is: The proportion of genes that are held in common by two individuals as a result of direct or collateral relationship.