I would say it is definitely always the owners/parents fault when it comes to animals/children. It makes me so angry when you hear of a dog being put down because of biting - surely it's been taught to do that? Or maybe not taught, but not told not too. It's like the whole Rottweiler/Doberman issue - I've had a Rottweiler and knew someone who had a Doberman in South Africa, now the Rottweiler was a huge softie - and she was supposed to be our guard dog! But, unfortunately, the person that brought her up before we took her used to beat her up and let her dogs attack her (we took two dogs, the other is a rhodesian ridgeback and also a big softie). The Doberman, same, the most timid creature ever that the owner actually took him to classes to try and get some spirit into him as he was worried about the dog being hurt if he was ever broken into. Obviously these are only two cases but a dog is very persuasive/trainable and will do anything it's owner tells it. These poor dogs are being put down due to the owners being at fault.
If you think about it, we have to have learn to drive and take a test to get a licence, maybe something similar should be brought about re dogs/animals. Admittedly I hate tests(!) but if this stopped unsuitable owners......