Breeding rarely has anything to do with a dog's temperment. His problem is that he was not trained properly when he was a pup not to do this. Teaching a puppy to have a soft mouth when he is young is one of the most important things you can teach him. Question: is he neutered? Dogs that are not neutered tend to have more behavioral problems then neutered dogs, this is not always the case though. He needs to be taught that biting or snapping even if if not intentional will not be tolerated. Flipping them on their back might work for a bigger dog, but not a small dog and I would not do any way. All of my dogs have been taught biting control. This way if he happens to bite you, it will not hurt because he will know how hard his bite is. So if he bites you, you can either yelp like a puppy, or say no in a firm but not raised voice. Then immediately after you do one of these two things, move away from him, and ignore him for a minute. The point to get across to the dog is that if he bites or snaps, no one is going to want to play with him or be around him. He will then quickly learn that if he wants anyone to play with him or be with him, he has to behave and not bite or even snap.
