A family business had bred dogs for over 250 years. During this time, 125 generations of dogs were bred for a single trait: protective instincts. Immediately after birth, the puppies are sorted based on whether or not they have a white patch of fur on their chests. Those without this trait, are no longer bred for their
business and instead are adopted to pet stores and not private sales for people requesting the desired trait of protective instincts.
How could the breeders know these other dogs will not have the traits they are looking for when they are just new-born puppies?