The standard definition of inbreeding is that it is any scheme which results in the sire and the dam having common ancestors. This common heritage is expressed by a parameter called the inbreeding coefficient, first proposed by Sewell Wright in 1922. Designated F by Wright (but more commonly IC or IBC by breeders), it can theoretically range from 0 to 100%, and indicates the probability that the two alleles for any gene are identical by descent. Though the primary consequence of inbreeding is to increase homozygosity, the IC is not a direct measure of homozygosity because the two alleles may be the same for other reasons. Within a breed, some proportion of all the genes will be the homozygous because there was only one allele to start with. In that sense, the IC may be regarded as indicating what proportion of the remainder have been made homozygous by inbreeding.The inbreeding coefficient is a function of the number and location of the common ancestors in a pedigree. The accuracy of calculations is dependant on all ancestors been know. For the purpose of this calculation we are going back five generations.
For information on the calculation and significance of the Coefficient of inbreeding, please read this article (.pdf format) from An Capaillín (2007) Pages 30-32 by Dr Michael G Diskin, Animal Production Research Centre, Teagasc, Mellow’s Campus, Athenry, Co. Galway, Ireland.
Extract from the paper showing minimum coefficient of
inbreeding for close relationships
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Calculate Coefficient of Inbreeding
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