It doesn't work like that. Dogs have 78 chromosomes, getting 39 from each parent. At the sixth generation, they inherit _on_average_ 1/64 of the genetic makeup from each ancestor, or _on_average_ about one chromosome. Because of the way chromosomes are reshuffled in breeding, though, farther back than the parents there is no way of knowing how much, if anything, a given individual contributed to your dog. In principle it is possible for a grandparent (2nd generation) to have contributed nothing. It is *probable* that one or more dogs in the sixth generation contributed nothing.subroc said:If the test shows 6, 8 or 10 generations back a dog with 25% something else was bred into your line are you going to contact AKC and have your registration rescinded? Would anyone contact everyone they sold a pup to and return their money?
There are also spontaneous mutations. I know someone who had a mismatch at one locus on the DNA profile of a puppy she bred. The other 9 1/2 matched, and the AKC or whoever was responsible certified parentage on the puppy. She contacted them and they said they inferred the mismatch was the result of a mutation.