The physical characteristics of an animal created by breeding a wolf to a dog are not predictable, similar to that of mixed-breed dogs. Genetic research shows that wolf and dog populations initially diverged approximately 10,000 years ago and have interbred only occasionally since; thus imbuing the dissimilarity between dogs and wolves in behavior and appearance. In many cases the resulting adult wolfdog may be larger than either of its parents due to the genetic phenomenon of heterosis (commonly known as hybrid vigor).(Wikipedia)
Wolf-dog hybrids are a mixture of genetic traits, which results in less predictable behavior patterns compared to either the wolf or dog. This is not to say that the behavior of any specific hybrid is erratic. It would, however, be unlikely that someone unfamiliar with an individual animal would be able to predict that animal's behavior with reasonable certainty. The adult behavior of hybrid pups also cannot be predicted with comparable certainty to dog pups, even in third-generation pups produced by wolfdog matings with dogs or from the behavior of the parent animals. Thus, though the behavior of an individual wolf hybrid may be predictable, the behavior of the type as a whole is not.The majority of high wolf-content hybrids are very curious and are generally more destructive than dogs.(Wikipedia)