Animal behavior, although 50% genetic; will be affected by the owner's behavior. If you do not train and feed your animal properly; all of them will be angry. There are animals who have devoured people because of lack of proper food and attention. Nurturing plays about the same percentage as nature in developing the animal's personality.
Have you heard the statement: "Dogs look like their owners?" That could be a compliment in some cases; in others it might be derogatory. So if you don't have a dog yet; keep that in mind when selecting one. Although this is said in a joking manner; when choosing your dog; it is very important that you get one that is similar to your personality - not your looks!
Animals do have personalities, and that is where nature or genetics play a major role; however, the owner's nurturing also has an effect on how the animal reacts. For example, if your pet; for example, a dog that comes from a breed that is known to be peaceful like the St. Bernard or Great Dane; but you have chaos in your home most of the time; that will definitely have an effect on your dog.
Do some research before bringing a pet to your home. Treat finding a pet as you would in finding a mate. Take some time, there is no rush to get that dog or other pet that you will hopefully keep for a long time.
If you are the type of person who does not have the time to nurture or train the dog; do not choose a bulldog; they have to be trained early on, otherwise they become aggressive. They are high energy and require a lot of mental stimulation, exercise, and lots of space. If you think you are bringing the dog to an apartment or other close quarters, you will have a problem.
Because animals do pick up some of the traits as the owner; be careful what you do or how you act around them. Dogs and cats are especially sensitive to their owner's emotions. Some are very protective and will react to people who they believe might be harming the owner. Then there are some dogs who don't like some people. One might ask: "Is this genetic or nature or is acquired or environmental?" No one knows that for certainty; although we do know that animals are intelligent; they can be trained to be peaceful if genetically from an angry breed.
Nature brings us here; but it is the nurturing that keeps us here! Nurturing plays the most important role in animal behavior.