WHAT IS GENETICS?

When we look at a dog, we see the individual in front of us: their appearance, structure, movement, behaviour and temperament. What we cannot see is the biological information that has contributed to making that individual unique. That information is contained within the dog's DNA, and the study of how this information is inherited, expressed and passed between generations is the science of genetics.

Genetics is fundamental to understanding dogs because it helps explain both similarity and variation. Puppies inherit genetic material from their parents, yet no two puppies in an ordinary litter are genetically identical. Each puppy receives a different combination of genetic variants from its parents, creating an individual biological starting point.

The basics of genetics

DNA, or deoxyribonucleic acid, is the molecule that stores biological information. It is organised into structures called chromosomes, which are found inside most cells. Sections of DNA that contribute to particular biological functions are called genes. Different versions of a gene are known as alleles.

A dog inherits one copy of each chromosome from its mother and one from its father. Consequently, a puppy receives genetic information from both parents, but the combination it receives is unique. During the formation of eggs and sperm, genetic material is shuffled and recombined, meaning that siblings can inherit quite different combinations of their parents' genetic variants.

This is one of the reasons a litter of puppies can contain individuals who share obvious family characteristics while differing considerably in appearance, behaviour, health and temperament.

Genes are not simple instructions

It is tempting to think of a gene as an instruction that produces a particular characteristic. Sometimes genetics does work relatively simply, particularly for certain single-gene traits. However, many of the characteristics we care about in dogs are considerably more complex.

Some traits are influenced by a single gene or a small number of genes, while others are polygenic, meaning they are influenced by many genes. Physical characteristics such as body size can involve numerous genes, and behavioural characteristics are often even more complex.

Temperament certainly cannot be reduced to a single gene. There is no single "good temperament gene", "Border Collie gene" or "high-drive gene" that determines how a dog will behave.

Instead, behaviour emerges from the interaction of many genetic influences with the developing nervous system, hormones, physiology, learning, environment and individual experience.

Genetics influences behaviour

One of the most important concepts in canine genetics is that inherited differences can influence behavioural tendencies.

Genetic variation can contribute to differences in characteristics such as activity levels, sociability, emotional reactivity, persistence, sensitivity to environmental stimuli, motivation and responses to novelty. These inherited influences can create predispositions, meaning that some behavioural responses may be more likely in one dog than another.

A predisposition is not the same thing as a predetermined outcome.

For example, a puppy may inherit a tendency towards greater environmental sensitivity. That does not mean the puppy is destined to become fearful. Its early developmental experiences, socialisation, learning history, environment and interactions with people can all influence how that predisposition is ultimately expressed.

This distinction is particularly important when discussing temperament. Genetics can influence the starting point, but the adult dog is the result of a much more complicated developmental process.

Nature and nurture work together

The familiar debate about whether behaviour is caused by "nature or nurture" creates a false choice. Genetics and environment are not competing explanations. They interact continuously throughout development.

A puppy's genes influence how its body and nervous system develop, including characteristics that can affect how it responds to the world. At the same time, the environment provides experiences that influence learning, emotional responses and behaviour.

This interaction begins before birth and continues throughout life.

Even puppies from the same litter experience slightly different developmental environments. Their experiences in the uterus may differ, as can their interactions with their mother and littermates. Once they leave the litter, their individual experiences diverge even further.

Consequently, genetically related dogs can develop noticeably different behavioural profiles.

Why littermates can be so different

It is common for people to be surprised when littermates grow into very different adults. One may be outgoing and confident, another more thoughtful and sensitive, while another may be particularly persistent or environmentally alert.

This does not mean genetics is unimportant. In fact, genetic differences between littermates are one reason such variation occurs.

Each puppy receives a different combination of genetic material from its parents. At the same time, development and experience influence how those inherited characteristics are expressed.

This is why responsible breeders should be cautious about making absolute predictions about a puppy's adult temperament based on a single observation. A puppy's behaviour at eight weeks provides useful information, but it is not a complete prediction of the adult dog.

Genetics and inherited disease

Genetics is also critically important when considering canine health. Some inherited conditions are associated with variants in a single gene, while others involve multiple genes and interactions between genetic and environmental factors.

Modern DNA testing has become an extremely valuable tool for breeders. For some known inherited conditions, genetic testing can identify whether a dog carries particular disease-associated variants and can help breeders make informed mating decisions.

However, genetic testing has limitations.

A dog that tests clear for every available DNA test is not genetically "clear" of all possible disease. Many canine disorders do not have a simple single-gene cause, and some conditions have no reliable genetic test. New disease-associated variants are also still being identified.

For this reason, responsible health-focused breeding involves more than collecting DNA test results. It requires consideration of the dog's overall health, physical examinations, breed-specific screening, family history, known health problems within related lines and, where appropriate, genetic diversity.

Genetics and the Border Collie

The Border Collie provides an excellent example of why genetics and behaviour are so closely connected.

The breed was developed through generations of selection for complex working abilities. Border Collies were not simply selected to be intelligent or energetic. They were selected for a combination of characteristics that enabled them to work effectively with livestock and respond to their handlers in demanding environments.

Modern Border Collies can therefore display strong inherited tendencies towards characteristics such as responsiveness, persistence, movement sensitivity, environmental awareness and intense engagement with their surroundings.

However, there is considerable variation between individual dogs.

A Border Collie can be highly motivated without being frantic. A dog can be sensitive without being fearful, active without being unable to settle, and highly responsive without being excessively reactive.

This variation is one of the reasons temperament should be considered carefully in breeding decisions.

The goal should not simply be to produce "more drive", "more intensity" or "more energy". The more useful question is whether the combination of inherited characteristics is likely to produce a balanced dog that is suited to the life it will actually live.

Genetics is not destiny

Perhaps the most important principle to understand is that genetics influences probability rather than guaranteeing an outcome.

A dog can inherit a predisposition without ever developing an extreme expression of that characteristic. Conversely, a combination of genetic factors may make a particular behavioural tendency more likely, particularly when environmental experiences reinforce it.

This is why genetics should never be used as an excuse for unwanted behaviour, nor should it be treated as a crystal ball that allows us to predict exactly what a puppy will become.

Genetics can help us understand tendencies, probabilities and risk. It cannot tell us precisely how an individual dog will develop.

What does this mean for responsible breeding?

Every breeding decision influences the genetic composition of the next generation. This makes breeding a responsibility that extends well beyond selecting two attractive or healthy dogs.

A thoughtful breeding programme considers multiple characteristics simultaneously, including health, temperament, structure, function and genetic diversity.

For temperament, this means looking beyond the individual dog. The temperament of parents, siblings, offspring and other relatives can provide valuable information about characteristics that may run within a family.

This is particularly important because a single dog can provide only a limited picture of its genetic contribution. Looking at patterns across a family can help breeders make more informed decisions.

Good breeding is therefore not about trying to eliminate every characteristic that could ever cause a problem. It is about understanding the genetic landscape as thoroughly as possible and making balanced decisions that improve the likelihood of producing healthy, stable and functional dogs.

The bigger picture

Genetics gives us an extraordinary insight into why dogs are the way they are, but it is only one part of the story.

A dog's behaviour is influenced by inherited biology, development, learning, environment, relationships and experience. These factors interact throughout the dog's life, which is why two dogs with similar genetic backgrounds can still become very different individuals.

For puppy breeders, understanding genetics helps inform responsible selection. For puppy families, it provides a more realistic understanding of what they can and cannot predict about their new dog.

A puppy is neither a blank slate nor a finished product.

Genetics provides the biological starting point, while development and experience help shape how that potential is expressed.

Understanding that distinction is one of the foundations of understanding canine temperament.

And it is also why genetics is such an important part of responsible Border Collie breeding.

Donna Williams,

Emerald Park Border Collies.

"My mission is to improve the life of at least one dog today!"