How can you tell if you have and Inbred/puppy mill puppy

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Does anyone know if there is any way that you can tell if a puppy is inbred? We bought one right before Christmas and she was a little devil! At just 7 weeks old she was constantly attacking our other dog and biting my 10 year old. Every time we would just be petting her she would all of a sudden start growling and turn around to bite. At our vets. advice we returned her to the pet store we bought her from. But they just turned around and re-sold her knowing that she has some issues. What would you have done?