Your Dog Wasn’t Born a Blank Slate: How DNA and Genetics Shape Behaviour

When we talk about dog behaviour, there is a tendency to place almost everything at the feet of training and socialisation. If a dog chases, pulls on the lead, barks at strangers, guards the house, struggles to settle or disappears after a scent, we often hear some version of, “It’s all how you raise them.” But dogs are not born as blank slates. Long before you teach your puppy to sit, walk nicely on a lead or come back when called, thousands of years of evolution and generations of selective breeding have already influenced the brain and body you are working with.

Genetics can affect how sociable a dog is, how readily it works with people, how strongly it wants to chase, how sensitive it is to movement, how quickly it becomes aroused, how persistent it is and even how it responds to unfamiliar people. You may have heard the claim that around 60% of a dog’s behaviour is genetic. The science is more complicated than assigning one exact percentage to every dog, but the principle behind the statement is important.

A large study involving behavioural information from more than 14,000 dogs across 101 breeds found that, when researchers compared differences between breeds, genetics accounted for an average of around half of the variation across a number of behavioural traits. For some traits, the estimated heritability was considerably higher. Trainability, stranger-directed aggression, chasing and attachment-related behaviour all showed substantial genetic influence. This does not mean that 60% of your individual dog’s personality is fixed and you control the remaining 40%. Heritability describes variation within populations, not a neat percentage of behaviour inside a single dog.

Another large genetic study involving thousands of dogs found that breed can provide useful clues about behavioural tendencies, but it cannot tell you exactly how an individual dog will behave. There is still enormous variation between dogs of the same breed. That distinction is incredibly important for owners, because genetics influence probabilities, motivations and tendencies rather than writing an unchangeable behavioural script.

A dog’s behaviour develops through an ongoing interaction between genetics, development, early experiences, learning, health, hormones, environment and training. Genetics might give one dog an extremely strong predisposition to chase moving objects while another barely notices them. Training can influence how those instincts are expressed, but it does not necessarily remove the underlying motivation. A Border Collie can learn not to chase bicycles, but that does not mean we have genetically transformed it into a dog that no longer notices movement. A terrier can learn an excellent recall around distractions, but training has not deleted generations of selection for persistence and predatory behaviour.

This is why good dog training should not be about fighting genetics. It should be about understanding the dog in front of you and teaching appropriate ways for those inherited tendencies to be expressed. The more we understand what a dog was bred to do, the easier it becomes to explain why certain behaviours appear so naturally and why some skills require considerably more work than others.

One of the most fascinating examples of the power of selective breeding comes from the famous silver fox experiment. The work began in the Soviet Union under geneticist Dmitry Belyaev and was later continued by Lyudmila Trut. Researchers worked with silver foxes, which are a colour variation of the red fox, and selectively bred them according to one main characteristic: how they responded to humans.

Foxes that showed the least fear and aggression towards people were chosen for breeding. Their offspring were assessed, and again the friendliest and least fearful animals were selected to reproduce. This process was repeated generation after generation. Over time, researchers produced foxes that actively sought human interaction and displayed much more sociable, dog-like behaviour.

What made the experiment especially interesting was that researchers were mainly selecting for behaviour, yet other characteristics began to change as well. Some of the foxes developed physical features such as different coat patterns, floppy ears and curled tails. Changes were also observed in stress responses and hormonal systems. In other words, selecting strongly for one characteristic appeared to influence other aspects of the animals’ biology too.

The silver fox experiment is sometimes simplified when it is discussed, and scientists continue to debate exactly how all of the associated changes developed. Nevertheless, it provides an important lesson. Genes do not always operate like isolated switches labelled “friendly”, “black coat”, “long legs” or “good at retrieving”. Many characteristics are influenced by multiple genes, and some genes can affect several biological systems at the same time. Selecting strongly for one feature can therefore influence other traits that were never the original target of the breeding programme.

Humans have effectively been doing something similar with dogs for centuries. Modern dog breeds were not originally created simply because people wanted dogs in different shapes, sizes and colours. Most were developed to perform particular jobs. Humans needed dogs that could locate game, retrieve birds, move livestock, guard property, control vermin, follow scent trails, protect livestock, pull sledges or work closely alongside people. The individuals that were particularly good at those jobs were bred, and their descendants were bred again.

Over many generations, humans were not simply changing the appearance of dogs. We were also selecting for behavioural tendencies, levels of persistence, sensitivity to movement, sociability, independence, scenting ability and willingness to cooperate with people. This is why understanding your dog’s breed, or the likely breeds behind a crossbreed, can be enormously useful.

Take Border Collies and other herding breeds. For generations, humans selected dogs that noticed movement, responded quickly to changes in their environment and could control livestock. Put those genetics into a modern suburban home without sheep and those instincts do not simply disappear. The dog may become fascinated by children running, bicycles, joggers, cars or other dogs. Some may stalk, circle or nip. Others become highly sensitive to everything moving around them.

Rather than asking why a Border Collie cannot simply ignore bicycles, it is much more useful to ask what that dog’s brain was bred to notice. Once we understand that movement sensitivity is part of the genetic picture, training becomes more realistic. We can work on impulse control, disengagement and alternative behaviours while also providing appropriate outlets for the dog’s need to use its brain.

Gundogs provide another good example. Labradors, Golden Retrievers, Spaniels and Pointers were all developed for different aspects of hunting, but they were generally selected to work cooperatively with people. Retrievers were bred to locate and bring back shot game, Spaniels to search vegetation and flush birds, and Pointers to locate game and indicate where it was.

These inherited tendencies can still be seen in pet dogs today. A Labrador that constantly carries shoes, toys and socks may be expressing a behaviour that humans deliberately encouraged for generations. A Spaniel that disappears into a hedge and becomes completely absorbed in scent is not necessarily being deliberately stubborn. Searching cover and following scent may be incredibly rewarding because of the type of work its ancestors were bred to perform.

Terriers bring a very different set of inherited tendencies. Many were developed to locate, chase and kill vermin. That required determination, persistence and the willingness to keep going even when the job became difficult. If a rat disappeared beneath a pile of straw, a terrier that quickly gave up would not have been particularly useful.

This helps explain why some modern terriers can become intensely focused on squirrels, rabbits, digging or movement. When a terrier appears temporarily deaf to its owner because it has spotted prey, we may be seeing generations of selective breeding in action. That does not mean we simply accept unsafe behaviour. It means recall, impulse control and sensible management may need to be particularly strong, while the dog should also have appropriate ways to satisfy its natural desire to chase, search and dig.

Scent hounds such as Beagles and Bloodhounds were selected to follow trails using their noses. When a Beagle picks up an interesting scent and suddenly appears to forget that you exist, the dog is not necessarily making a calculated decision to disobey. Following scent can be enormously reinforcing. Owners of these breeds should understand that recall may require much more training and proofing around scent than it might for a dog whose ancestors were not selected for independent tracking.

Sighthounds such as Greyhounds, Whippets and Salukis were developed to detect and pursue prey visually. Rapid movement can therefore trigger extremely powerful chase behaviour. These dogs can certainly learn recall and impulse control, but owners should still respect the strength of that genetic predisposition. A beautifully trained Whippet is still a Whippet, and sensible management around wildlife remains important.

Guardian breeds present another example of how history influences behaviour. Some dogs were deliberately selected to protect livestock, property or people. For a livestock guardian working independently, being suspicious of something unfamiliar could be useful. A dog that automatically welcomed every stranger into its territory would not have been very effective at its job.

In a modern environment, those same tendencies can become more difficult to manage. Delivery drivers, visitors, children, cyclists and neighbouring dogs are all part of everyday life. Early socialisation, thoughtful exposure and good training are extremely important, but owners should also recognise that not every breed has been genetically selected to be highly sociable with unfamiliar people. Expecting every dog to enthusiastically greet every stranger is unrealistic.

Even companion breeds have been shaped by genetics. Dogs developed primarily to live closely with people were selected for characteristics that made them suitable companions. They may have been more likely to remain close, seek social contact and cope with living in homes. This is why two dogs of exactly the same size can behave completely differently. A small terrier and a small companion breed may weigh the same, but generations of selective breeding have created very different motivations and behavioural tendencies.

Genetics become even more interesting when we look at health, because selecting for one visible characteristic can sometimes have unintended consequences. One of the clearest examples involves pigmentation and deafness. Most owners have heard that white dogs can be more likely to be deaf, and in certain breeds and with particular pigmentation genes there is a genuine association.

This does not mean that every white dog will be deaf. The genetics are far more complicated than that. However, pigment-producing cells called melanocytes play an important role in the normal development and function of the inner ear. Certain genes that affect pigmentation can therefore also increase the risk of congenital deafness. This connection has been particularly well documented in breeds such as Dalmatians, and associations between excessive white pigmentation, blue eyes and deafness have also been identified in some other breeds.

Merle colouring provides another example. Merle creates the attractive mottled or marbled coat seen in a number of breeds, but the genetics responsible for merle can also be associated with hearing and eye abnormalities. The greatest concern occurs when two merle dogs are bred together, because puppies inheriting problematic combinations can have a much greater risk of sensory defects. This demonstrates why breeding purely for fashionable colours without understanding the genetics behind them can have serious welfare consequences.

Body shape can be affected in similar ways. Humans have deliberately selected some breeds for extremely short legs. Genetic changes involving FGF4 help produce the characteristic short-limbed appearance seen in breeds such as Dachshunds, but some of these genetic variants are also associated with an increased risk of intervertebral disc disease. A feature that humans find appealing can therefore be linked with an increased health risk.

We see similar concerns with extremely short-faced, or brachycephalic, breeds. Dogs such as French Bulldogs, Pugs and Bulldogs have been selectively bred for increasingly shortened skulls and flat faces. Unfortunately, extreme brachycephalic conformation is strongly associated with breathing difficulties and Brachycephalic Obstructive Airway Syndrome. Once again, selecting strongly for a particular appearance can have consequences for health and quality of life.

This does not mean selective breeding is automatically bad. Selective breeding is the reason we have the extraordinary variety of dogs that exist today, and responsible breeders can use genetic testing, health screening and careful pedigree selection to reduce risk. The important point is that biological traits do not exist in isolation. When we strongly select for one feature, whether behavioural or physical, we need to understand what else may be travelling alongside it.

Crossbreeds are not exempt from genetics either. Crossing two breeds does not somehow remove the behavioural characteristics of both parents. A Cockapoo, for example, does not stop carrying Cocker Spaniel and Poodle genetics simply because it is a crossbreed. One puppy may inherit stronger behavioural tendencies from one side of the family, while a littermate may express a different combination.

Genetics shuffles the deck. It does not take exactly 50% of every visible, behavioural and health characteristic from one parent and neatly combine it with 50% from the other. This is why two puppies from the same litter can differ significantly in confidence, sociability, arousal, persistence and prey drive.

Understanding genetics should never become an excuse for poor training or management. Saying, “He’s a terrier, so he will never recall,” is no more useful than pretending breed makes no difference at all. Genetic predispositions influence what may come more naturally to a dog, what they find particularly rewarding and how much training certain behaviours may require. They do not mean improvement is impossible.

Socialisation matters. Training matters. Experience matters. Health matters. Hormones matter. The environment matters. Most importantly, the individual dog matters. Genetics and breed can tell us what may be more likely, but they cannot give us a complete personality profile before the dog has even been born.

This is why prospective dog owners should look much further than appearance when choosing a breed. Before getting a puppy, ask what humans originally created that dog to do. What did its ancestors need to notice? Were they expected to chase, guard, retrieve, search, herd or work independently? Was persistence important? Was barking useful? Did they need to cooperate closely with people, or were they expected to make decisions for themselves?

Those questions can tell you far more about what life with that breed might be like than simply looking at photographs.

If you are choosing a breeder, ask about temperament as well as health. Meet the mother where possible and ask about the behaviour of other dogs in the family. Find out what health testing has been carried out and whether the breeder is selecting dogs based on stable temperament and good health rather than simply producing fashionable colours or exaggerated physical characteristics.

When you bring home a puppy, you do not simply bring home eight weeks of life experience. You bring home DNA, breed history and generations of selective breeding. Training then helps shape how all of that inherited potential is expressed.

The more we understand what our dogs were genetically designed to do, the less likely we are to label perfectly predictable behaviour as stubbornness, dominance or deliberate disobedience. Instead, we can provide appropriate outlets, put sensible management in place and train the dog that is actually standing in front of us.

Your dog’s DNA does not completely determine who they will become, but it absolutely deserves a seat at the table whenever we talk about behaviour.