Most people love their dogs deeply and feel hurt, guilty, defensive, and protective when it transgresses. He was protecting his owner, was abused by the former owner, was startled. . . The list of reasons is only limited by the owners' imaginations You will seldom be in a position to judge the accuracy of their reasoning, and if you like the dog, your regard may shade your opinion, too. Because the willingness of the dog to bite a person has a genetic component, the safest option in breeding is to select dogs that have never done so. While the height of the threshold at which a dog will bite may be initially determined by inheritance, it can certainly be raised or lowered by training.
Puppies begin learning it from each other and from their mother.
The strength with which they bite is tempered by the response of their playmates. The hurt puppy protests with a loud, high-pitched scream, and the offending puppy lets go. Likewise, nursing puppies can bite their mother once their teeth come in. Mom reacts by moving away from the puppy, pushing it away, or, in extreme cases, by growling at the biter. In these ways, puppies learn to set limits on the force they exert when biting.