Genetics and Dog Aggression

As we have seen throughout this series, there are many factors that can contribute to dog aggression, most of which can be avoided or resolved by providing dogs with holistic, balanced training, socialization, leadership and a fulfilling lifestyle. That being said, some dogs simply come pre-wired to be more prone to display aggressive behavior than others. Many dogs also come pre-wired for the behaviors that are often associated with aggression such as Hyperactivity, Fear or Dominance. In other words, sometimes the root of a dog’s aggression is learned and sometimes it is genetic or biological. Most likely it is a combination of both. 

In the right hands, these “spirited” dogs can be some of the best dogs in the world. However, in the wrong hands, their spiritedness can be a real-life nightmare. These dogs tend to be high maintenance, which means they need owners who are ready, willing and able to go the extra mile…or the extra 10 miles as the case may be.  

Are your hands the right hands for a “spirited” dog? I don’t know, let’s see: 

Is training and exercising the dog a priority for you or will the dog fall to the bottom of your to-do list? Are you too busy with work, kids and other priorities to have time for a high maintenance dog? Think carefully before answering. I’m talking several hours a day dedicated to training, exercising and socializing the dog. I’m talking about serious, high distraction, high control-oriented training, not just exchanging tricks for treats in the living room. Are you up for that? 

What about leadership? Are you a leader or a coddler? Do you think dogs are furry babies or do you realize they are basically domesticated wolves? Seriously, this is not a joke! It’s ok if you are a coddler, just embrace that about yourself and get a dog that is coddle proof, which is to say, don’t get one of the spirited dogs we are talking about right now. Coddlers will ruin a dog like this, for sure, one million percent, every single time…unless they can learn to stop coddling and become a leader. 

Training, leadership and lifestyle can make a huge difference in how pre-wired aggressive tendencies show themselves, or if they even show themselves at all, but choosing a dog with an aggressive makeup comes with a much higher level of commitment and responsibility than choosing a dog that is pre-wired to be calm and cuddly. 

Let’s look at what might predetermine a dog’s aggressive tendencies: 


  • Breed matters.  
    • Humans have selectively bred dogs for various traits for millennia…it’s a thing. 
    • A German Shepherd is not just a Labrador in a different coat. 
    • It is not doggy racism to note that certain breeds tend to have certain characteristics. 
    • One of the traits that has been bred into some breeds and out of others is aggression. 
  • If everyone in the world suddenly decided to do more research and make more intelligent breed choices all the professional dog trainers and behaviorists in the world would be looking for part time jobs because at least half our business would go away.
  • Getting clear about what you want from a dog and, perhaps more importantly, what you are willing to put into a dog will help you make the right breed choice for you and your family. 
  • Breed is not a guarantee of any particular behavior but it is a good predictor of a certain range of behaviors. 
    • There are always exceptions to “breed standards” but, generally speaking, it is wise to anticipate the behaviors that the dog has been bred for.
      • Breed tendencies, including aggression, often don’t show up until the dog matures, which makes a lot of people make poor puppy choices. 
      • Puppies are like babies, all of them are sweet, then they grow up. 
    • There are breeds that are known for being protective, such as German Shepherds or Rottweilers. 
    • There are breeds that are known for being high energy, such as Australian Cattle Dogs or Border Collies. 
    • There are dogs that are known for being friendly, such as Labrador or Golden Retrievers. 
    • There are breeds that are known for being great lap dogs, such as Pugs or Cavalier King Charles. 
    • There are also different lines within each breed, such as working lines or pet lines, which can be dramatically different. 
      • Working lines tend to be much more intense and high strung.  
    • There are also individual temperaments within each litter of pups. 
  • Some breeds are more prone to be aggressive than others due to being selectively bred for aggressive purposes such as guarding, protecting, fighting, etc. 
    • This does not mean they will necessarily be aggressive but it is more likely that they will be. It is also more likely they will be intense about it if and when they are aggressive.  
  • Some breeds, while not always prone to aggression, are simply more dangerous if they do happen to become aggressive due to their size, power, bite strength, etc. 

Inherited Predispositions

  • Aside from the influence of breed, dogs of any breed can inherit a genetic predisposition for aggression. 
  • Often it is not the aggression that is directly inherited as much as it is the other tendencies that lead to aggression such as Fear or Hyperactivity
  • Russian fox experiments: Starting back around the 1950s there were some studies done by a Russian geneticist that showed how powerful genetics are on behavior. 
  • The main thing everyone talks about is how they developed a very tame version of silver foxes by mating the ones that showed the least aggression and most friendliness towards the researchers to each other. Within a few generations they had foxes that started to behave like domestic dogs. Not only that, they started to look like dogs as well. I am not 100% sure but I believe these studies are still ongoing. 
  • I can’t say for sure, because it was a long time ago, but I think I remember seeing a documentary on this that mentioned mating the fiercest foxes with each other as well. As expected, the result was more aggressive foxes. I don’t think that part was continued and I never hear it talked about these days. Either my memory is off or it was swept under the carpet. Regardless, it stands to reason that aggression could be passed on genetically just as easily as tameness. 

Prey Drive

  • Most dogs have a natural predatory instinct that makes them chase, catch, bite and shake things.
    • Some breeds are prone to have higher prey drive than others but most dogs have it to some degree.  
    • Some dogs have a tame version that is limited to stalking and chasing without biting while others may have the full-blown chase and kill version or anything in between. 
  • Prey drive can be directed towards things that are not really “prey” such as kids, runners, bicyclists, skateboarders, cars, etc. 
  • Prey drive can be directed into appropriate behaviors like fetch and tug. 
  • Prey drive can also be a part of how dogs chase and play with each other, which is perfectly fine unless it goes too far. (see: Overly-Intense Play

Protecting and Guarding  

  • Guarding and protecting, like prey drive, are instinctive behaviors that most dogs have to some degree, although there are some dogs that are so tame that it seems they were holding the door open for everyone else when that gene was being passed out.
  • Some breeds have historically been used for guarding and protection, so they will predictably be more prone to this form of aggression. 
  • See: Part 10: Guarding/Protecting

Chemical Imbalance or “Mental Illness”

  • DISCLAIMER: I am not a neurologist or a geneticist or anything other sort of ist, I am just a dude that trains dogs (and people) for a living, so I can speak to this topic based only on personal and professional observations.  
  • In my experience, I have found that it is very rare that aggressive dogs actually have anything that appears to be a genetic chemical imbalance or “mental illness” that requires, or is helped by, psychotropic medications. 
  • I have had clients tell me their dogs were calmed by these meds but not enough to stop the aggression. More often than not they simply say the drugs didn’t work. 
  • I have never come across a dog that had been through significant amounts of advanced, balanced, holistic training before the meds were prescribed. 
  • I have never had a client tell me that their dog had been tested for confirmation of a chemical imbalance before being prescribed psychotropic meds.
  • Maybe drugs are needed, maybe not, but, if they are being prescribed before significant training has been attempted or by someone who believes dominance is a “mental illness” or that aversives have no place in dog aggression rehab, I would be more than just a little bit skeptical. (See: Part 7: Dominance)
  • The evidence for my opinion on the overprescribing of drugs and misdiagnosis of “mental illness” is simply my professional experience and observations of behaviors that were suggested to need medication being resolved with balanced training and lifestyle changes without the need for medications. 


Genes have a huge impact on behavior but they don’t dictate everything, environmental factors also have a huge impact on behavior. It’s the old “nature vs nurture” argument but there is really no argument because it is both nature and nurture that ultimately dictate how a dog turns out. This includes whether or not the dog behaves aggressively at all or how intensely the aggression expresses itself and how the dog responds to obedience training such as being told to “Leave It” when reacting aggressively. So, in short, choosing a dog that is a good fit for you would be a good start. After that, it’s up to you to be a good fit for the dog you have. 

Chad Culp – Certified Dog Trainer, Canine Behavior Consultant, Owner of Thriving Canine. 

© Thriving Canine 2022

We offer in-person training in the San Francisco Bay Area as well as virtual consults anywhere in the world.




Thriving Canine University private Facebook group. (please read the rules before joining)

Please use the links below to follow the whole series for a more complete understanding of the triggers and underlying factors of dog aggression.

Related Content: