Is behavior inherited?
Behavior is inherited but heavily influenced by environmental factors. How much is “nature” and how much “nurture” is a debate that is still raging in scientific circles, not to mention among dog trainers. Certainly, aspects of behavior are inherited: Pointers point, sled dogs pull, and stockdogs herd. Disposition is also to some degree inherited – hounds are laid back and Border Collies intense. Other types of behavior may also be influenced by genetics; there is evidence that very small size and a tendency to bark a lot are connected.
What percent of temperament is inherited?
At present there is no way to put hard numbers to it. People tend to think it must be caused by environment or by genes. The fact is a dog’s genes and its environment intertwine from the moment of conception. Together they produce what we observe in the dog. A dog could have all the best genes for temperament and be ruined by a terrible environment. Likewise, a genetically marginal dog might prove quite acceptable in an ideal environment. What is “terrible” and “ideal” will vary from one person to another depending on their needs and expectations. The perfect dog for an elderly lady who likes her home to be calm and quiet won’t be a good prospect as a military dog, or vice versa.
That said there are certain behavioral traits that clearly run in families and therefore are of high heritability, meaning it requires more genetic input than environment to reach the final result. Noise phobia, sometimes called sound shyness, is an excellent example of a highly heritable defect of temperament. Noise phobia is an exaggerated fear of thunder, fireworks, gunshots, etc. The 2009-10 ASHGI health survey indicated that a third of Aussies have some degree of noise phobia.
If you observe any behavioral trait in a group of closely related dogs and those dogs live in different homes and come from different litters, odds are there is a strong genetic component to that behavior.
How do we breed for good temperament?
Temperament (or disposition, as some would prefer) develops from both genetics and environment. Certainly, traits like sound sensitivity and aggressive behavior toward other animals or humans runs in lines and in some breeds. Temperament is to some extent genetically controlled, but it can also be “created” by environment. That said if a dog has significant temperament faults or its disposition is atypical for the breed, it should not be used for breeding.