Creating a breeding relationship from unusually close members of the same family is called inbreeding. Done consistently, it will push the breeding coefficient well above 0.25, and It is done to concentrate the DNA of like members of the same family usually within in a type or breed of canine, livestock animal or even some wild animals.
When occurring within a wild population, inbreeding usually happens when isolation is coupled with successful survival skills. The ponies of the off shore Islands in the eastern USA or Western feral wild horses and Australian Dingo dogs are examples of this type of adaptive success in the wild. Limiting the inbreeding factor in wild populations is accomplished by expelling young bachelor offspring from herds or packs. In canine groups, the alpha male and female are the only mated pair. To accomplish mating lower ranked dogs or bitches must leave the pack and establish their own family group pack. Inbreeding is controlled or eliminated altogether. Monitoring the assemblage of a breed’s pedigree closely is the way breeders of domesticated animals accomplish the same task and become the alpha dog of their own pack.
Inbreeding often creates breeds from general types of dogs with particular talents or attributes that serve the needs or spark an intimacy issue with their human companions. Excellent noses for game, a talent for gathering or moving livestock or guarding the goods and property of men and their families are all reasons for mating one individual with another dog good at the same task. Then breeding the sons and daughters of those same base animals together and back to their parents can create more animals good at these tasks and eventually forming a breed entity.
Inbreeding done with purposeful intent and careful selection is not always harmful. It brings harmful and defective genes to the surface where they can be seen, assessed and avoided in future matings. But it should never be done by breeders unless strictly controlled, limited and carefully planned. Often breeders will make a close breeding to locate the source of a defect that popped up unexpectedly in a previous outcross breeding. Breeders who routinely use line-breeding methods may make an outcross, pick up something they did not anticipate, and then want to find out from where it surfaced. They may inbreed to locate that portion of the pedigree thought to harbor the progenitor of the defect, or to eliminate current breeding prospects from an available progeny of the breeding pair where the defect arose.
Most examples of productive inbreeding are seen in commercial breeding programs dealing with laboratory animals or livestock. For the past fifty years or more laboratory mice and rats have been bred from the same strain of brother sister mated animals, and the same bull may father entire herds of related cattle in countries all over the world using banks of enhanced collected sperm. In dogs, cryogenic sperm storage and enhancement is one of the fastest growth areas in serious dog breeding industry. In Tibetan Spaniels that technology has become useful. Recent breedings of the deceased stud dog Tashi Dordje by his owner Marguerite Perkins Garrick produced several get from the 35 year old stored sperm. An important inbreeding among Tibbies took place when brother and sister Bimbo and Dido produced what became the progenitor of a whole line of BIMs Tibbies in the 70s USA. In fact nearly the entire future of Tibetan Spaniels happened because of the inbreedings among of several original imports into England in the mid to late 40s. Many breeds owe their current status as recognized breeds to inbreeding. The Boxer breed in the United States is based on breedings among the get of only four major stud dog imports of closely related German stud dogs from the Von Dom line.