Some dogs are more prone to attack because of their genetic background. ALL dogs have the potential to be nice and ALL dogs have the potential to be mean. (and there are some out there that are just bad, no matter how they are raised) Most large dogs (and dogs with large jaws) were bred for a purpose… to hunt, to herd, to work, whatever. Even if they are not RAISED doing those things, it is still in their nature.)(Look at herding dogs who will herd kids) While the majority of the dogs temperment is based on how it was raised, some dogs (Chows, Bulldogs, pits, rotts) have a disadvantage because of their past. This is NOT to say that these dogs will turn… only that it may take less provocation to make them do so.