How to train a puppy?

As puppy mills commonly trade breeding stock back and forth, the gene is introduced into other mills (in exchange with Fox Terrier or Poodle infused particolors, etc.) and so the white gene becomes firmly established in that population. Commercial breeders sell to pet stores, and these form the genetic basis of the vast majority of "backyard breeder" dogs. As none of these animals are bred for the show ring, the fact that they do not exhibit quality in type is irrelevant. Crossbred animals would have very great difficulty surviving in the show-breeding gene pool — they would find it difficult to win or produce offspring who could.