Nature vs. Nurture

Putting the myths to rest

When the subject of the American Pit Bull Terrier* comes up, the issue of nature vs. nurture is always a hot topic. Over the years, varying schools of thought have evolved with respect to the dog fighting heritage of the bull breed and their inclination toward aggressive behavior.

Before we go any further, let's get one thing out of the way right off the bat. Throughout history, many breeds of dogs were used in dogfighting. The Romans fought dogs in their great arenas long before the American Pit Bull Terrier ever came into existence. Fortunately, civilization has evolved, and the barbaric sport of dogfighting is no longer tolerated. The decedents of those various dog breeds once used in the gladiator arena are now service dogs, therapy dogs and family companions.

Nevertheless, regardless of their experience with the APBT, or the lack of any expertise related to the study of science and/or genetics, those who support breed specific legislation (most commonly in the form of "pit bull bans") are adamant that genetics play a crucial role in the disposition of the American Pit Bull Terrier. They argue vehemently that because some unscrupulous breeders once bred and used the APBT for dogfighting, the breed poses an imminent danger to the public and, thus, are not suitable pets in today’s society. Some even go so far as to classify the APBT as their own "species."

On the other end of the spectrum, those who have experience with the APBT argue that it is a dog’s environment - its training, socialization and, most importantly, interaction with its owners - that produces a good or a bad dog. They further argue that while the APBT may have initially been selectively bred by some to be fighters, over the past several decades, they have been selectively bred to not be fighters, thus producing a breed of dog that makes an excellent companion and working dog. Quite frankly, their temperament and disposition develop just like any other dog - at the hands of their owners.

Fortunately, science is always making advances, and the field of genetic study is rapidly growing. Recent studies indicate that genetics alone are not as important in the development of specific traits and personalities as once thought. Moreover, those studies support that outside factors influence behavior as much as, if not more than, genetics.

In spite of a growing emphasis on genetic factors in shaping who we are, the pendulum that swings between the extreme positions in the nature/nurture debate still has plenty of momentum, fueled by facts on both sides. No one can argue seriously with the idea that genes make important contributions to personality. Animal breeders long have known that it takes only a few generations of controlled mating to influence such behavioral traits as fierceness or tameness in dogs.  

One of the most important contributions of modern neuroscience has been to show that the nature/nurture debate operates around a false dichotomy: the assumption that biology, on one hand, and lived experience, on the other, affect us in fundamentally different ways. Research has shown that not only do nature and nurture each contribute to who we are, but also that they speak the same language. Both achieve their effects by altering the synaptic organization of the brain. The process by which experience shapes synapses is referred to as "synaptic plasticity." Although a great deal of synaptic plasticity occurs during early childhood as the brain is developing, plasticity in the form of learning and memory continues to shape our synapses throughout our lives. [1] LeDoux.

Obviously, based on Dr. LeDoux’s research above, the brain continues to take in and process new information over the course of the entire lifetime. Living creatures can and do learn their entire lives, and their reactions to what they learn are molded by the outside environment and experiences.  

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 Muddling the whole [nature vs. nurture] debate is the finding that gene expression is influenced by the environment. Turns out genes have what are called epigenetic markers. Acting like a volume knob for genes, these tags adjust the intensity of gene expression. Identical twins are born with the same epigenome. But over time, environmental factors such as chemical exposure, diet and other lifestyle differences can alter these markers. This discovery has added another layer of complexity to the nature-versus-nurture matter: For instance, finding that identical twins don’t both display a disorder such as addiction, doesn’t mean that addiction is not genetic. [2] Kranzler.

Dr. Henry Kranzler, University of Connecticut School of Medicine, goes on to state that "genetic predisposition is not destiny.”

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Adoption studies have also somewhat shown that a persons environment plays an important role in his mental ability. For example, a study done with adoptive children raised in the same house had very similar IQs, given that these children were in no way related genetically. The environment that they we raised in provided them with similar abilities for learning and for retaining information. Kagan, Jerome, and Earnest Havermann. Psychology: An Introduction. 4th ed. New York: Harcourt Brace Javanovich, Inc., 1980. 

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Fraternal twins (who share approximately half of their genes) present an informative contrast. Because they are raised in the same environment but are not genetically identical, they help us to see the influence of environmental factors (Segal, 69). These factors are all valuable to the environmentalist argument.  

In addition, if environment didn't play a part in determining an individual's traits and behaviors, then identical twins should, theoretically, be exactly the same in all respects, even if reared apart. But, as we saw earlier, a number of studies show that they are never exactly alike, even though they are remarkably similar in most respects. Segal, Nancy L., Ph.D. ‘New Twin Studies Show…’ Psychology Today Oct. 1999: 54-59 and 69-70. [3] 

At this point, I am quite sure those who zealously support and encourage "pit bull bans" are scoffing. How does the study of human genetics have an impact on what we know about canine behavior? Well, I’m glad you asked. There are genetic similarities in canines and humans. Canines are being used more often to research human behavior and disease. Moreover, an array of animals, from rats to monkeys, have been used routinely over the last century to uncover the mysteries of human behavior, thus indicating that the study of genetics in all mammals is relevant to the study of canine genetics and behavior.

 For example, a study conducted with mother rats and their offspring yielded the following conclusions with respect to genes and behavior: 

A learned trait like bad mothering can be passed on without needing a new gene at all. This ability to change genes, suppress or encourage them, turn them on and off, etc. was unknown until recent years. But the new research goes farther, because the [rats’] behavior has to come from the brain, and in order for the brain to trigger any behavior, genes have to fire. Genes aren’t automatically triggered or "light up." They can express themselves a little or a lot or not at all. In the case of the rats raised by good mothers, their brain genes expressed to a high degree for traits like self-confidence, sociability, and resistance to stress. The rats who were under-mothered have the same genes, but theirs didn’t "light up." They remained unexpressed.

What this means is that both nature and nurture are involved. A gene may exist for specific behaviors, but outside influences still have a great deal to say. Your Genes Didn’t Make You Do It, Deepak Chopra, August 2007. [4]

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David Reiss, a psychologist with George Washington University conducted a twelve year study involving 720 pairs of adolescents with different genetic relatedness (from identical twins to step-siblings). His study showed strong proof that genetic tendencies are encouraged, or stifled, by specific parental responses.

Biology is not destiny. Many genetic factors, powerful as they may be in psychological development, exert their influence only through the good offices of the family. The Relationship Code, David Reiss, Harvard University Press, 2000 [5]

Quick interpretation of Dr. Reiss’ research: How parents raise their children actually does matter. Far from the original school of thought, genes do not serve as blueprints for behavior, but instead interact with the environment to create who we are. 

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In his book, Nature v. Nurture, Matt Ridley expounds upon this theory:

Genes themselves are implacable little determinists, churning out utterly predictable messages. But because of the way their promoters switch on and off in response to external instruction, genes are very far from being fixed in their actions. Instead, they are devices for extracting information from the environment. Every minute, every second, the pattern of genes being expressed in your brain changes, often in direct or indirect response to events outside the body. Genes are the mechanisms of experience. Nature v. Nurture, Matt Ridley, HarperCollins Press, 2003 [Emphasis added.] [6] 

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In summary, the belief that genes predispose any living creature to one disposition or another is losing its standing among the scientific community. Rather, most scientists now theorize that both genes and environment play integral roles in behavior and behavior development. More specifically, in relation to the topic at hand, YOU, the dog owner, play an important role in the development of your dog's temperament.  According to research, behavior changes throughout a lifetime in connection with experience lived during that lifetime.  New, positive experiences and stimulation can encourage and promote positive behavior – even after negative experience has occurred.    

It is time for the proponents of breed specific legislation who continue to play the "dogfighting card" stop bluffing and show their entire hand.  They choose not to do this because they have no other arguments.  They selectively pick and choose the information to divulge so that it appears they have a valid argument against the APBT when they do not. 

Those who support pit bull bans would like us to believe that the American Pit Bull Terrier as a breed, in general, possesses some sort of "dogfighting gene,” and for this reason, the APBT is not suitable for today’s society.  For those who support this factually weak argument, its convenient to play the dogfighting card because it instills fear in those who are uninformed. This argument assumes that if the American Pit Bull Terrier was bred to be used for dogfighting a hundred years ago, the APBT obviously must pose a danger to the public today. However, what the supporters of breed specific legislation conveniently "forget" to include in this argument is that the APBT has always, from the beginning, been selectively bred to be excessively human friendly. Human aggression was culled - yes, even by those breeding dogs to fight a hundred years ago - aggression towards humans is, and has always been, an unacceptable trait in the breed. The desire to please and the natural inclination for human companionship and affection have been bred into the APBT since the inception of the breed, while the "gameness" has been bred out of the line by responsible breeders over the past several decades.  

The manner in which you raise your dog ultimately determines what kind of dog you will have...good or bad, friendly or reclusive, gentle or aggressive. Genes alone do not make this determination, and as current scientific research confirms, it is nonsense to hold on to such a played out theory.  

Finally, this essay is in response to those who say the APBT poses a danger to the public because of the breed’s historical involvement in dogfighting. The scientific research shows that to be false - that even "IF" something to the equivalent to a "dogfighting gene" existed, the manner in which a dog is raised would manipulate and repress that gene.  

Nevertheless, I'm not suggesting APBT owners should run out to their local dog park.  (Personally, I'm not a fan of dog parks, and I don't think any dog, regardless of breed, should be allowed to run loose with multiple dogs...a "pack mentality" can develop and ultimately lead to problems.)  In effect, what I am saying is that owners need to understand their individual dogs. Dog owners must realize the key role that socialization and training play in the development of the temperament of their dogs. If, after socialization and training, your dog still doesn’t particularly care for other dogs, then don’t put him in a situation where he could get into trouble. You are responsible for your dog! Don’t set your dog up for failure - help them to be the best canine citizens they can be. If we do this - if we take a stronger role in the development of our dogs’ temperaments - one day, breed bans can be a thing of the past. 

In closing, we see that over the course of a lifetime, the brain is continually changing and processing new information, thus answering the question...Yes, Virginia, you can teach an old dog new tricks. Maybe with enough common sense research, we can even change some human minds on their beliefs with respect to the American Pit Bull Terrier.

 Jodi Preis, Bless the Bullys


 *For the purpose of simplicity, I refer to the American Pit Bull Terrier or “APBT” throughout this essay.  To clarify, it should be noted that I am referring to the American Pit Bull Terrier, American Staffordshire Terrier, Staffordshire Bull Terrier and any and all dogs that typically fall under the category of "pit bull" and who face legislation, stereotyping and bias under the catch-all term “pit bull.”   

 **It should be noted that I am not a scientist, nor am I an “expert” on the American Pit Bull Terrier.  Rather, I am a responsible pit bull owner, as well as a pit bull rescuer.  Over the nineteen years, I have shared my life with “pit bulls,” the last fourteen of which have been spent with multiple pit bulls – all coexisting peacefully under one roof and in my personal care.  My experiences with the many pit bulls that have passed through my front door not only qualify me to speak to the temperament of the breed, but my commitment to the breed demands that I defend them from those who have no qualifications, training or expertise to render judgment either for or against the breed.  Knowledge is a powerful tool, and if used wisely and effectively, all pit bull advocates can change the image of the breed.  In the end, it is fact that will win over uneducated and biased opinion.    


 [1] Joseph E. LeDoux ( is a professor of neural science and psychology at the New York University Center for Neural Science and the author of The Emotional Brain (Simon & Schuster, 1996).

 [2] Nature v. Nurture: The mysteries of individually unraveled.

 [3] Neuroscience for Intelligence: Evidence for Nurture.

 [4] Your Genes Didn’t Make You Do It, Dr. Deepak Chopra, August 2007.

 [5] The Relationship Code, David Reiss, Harvard University Press, 2000

 [6] Nature v. Nurture, Matt Ridley, HarperCollins Press, 2003.