Puppies play with littermates by nipping and biting each other. They need to be discouraged from playing this way with family members from the start. There are a few things that you can do to curtail this behavior. When your puppy is very young, always keep a toy in your hand to divert your puppy’s attention away from your hands. When he bites your hands, move the toy around to attract his attention away from your hand. If your puppy isn’t interested in your toy, try another one. If he continues biting you, tell him in a fairly loud firm voice “no” and turn away and ignore him until he quits biting. If he still insists on biting, put a collar and leash on your puppy and tether him to a chair or door knob. Don’t get close enough to his reach until he stops this behavior. Praise your puppy when he settles down to playing appropriately and only after he has quit this behavior do you re-enter the area that he can get to.
Consider if your puppy has had enough exercise. Puppies tend to get overly nippy when they have too much energy that needs to be expelled through outside exercise.
Children tend to play with puppies in ways that encourage them to bite and nip. Running around and playing rowdy will encourage puppy nipping. Children need to be taught how to play with puppies just like puppies need to be taught how to play with children.