Dogs are not born aggressive. it is the human behind the dog that makes them what they are. However, there are powerful breeds, Pitt Bull, German Shepherds, Rottweilers, Dobermans, etc, but an idiot dog owner can turn any dog, any breed, aggressive. Sometimes, without proper knowledge, people create problems, and don't even realize their doing it. Absolutely, NO wolf hybrids, It takes a"truck full of knowledge", and then there is no guarantee that there won't be serious problems. In some states it is illegal to sell wolf pups, and wolf mixes.