Ever Ask Your Dog “Why Are You Like This?” DNA Is the Answer — Kind Of

This study says it’s actually less about what’s in their DNA and more about what’s on it.

March 2, 2023

If your dog is the most loving, affectionate, agreeable dog ever, is it because of the perfect early socialization you provided? Is it due to the constant attention you gave them in the first month, even if it did cost you all your vacation time? Is it good genes that deserve the credit? And if your dog has some serious issues — extreme fear, high reactivity, a tendency to use their mouth on everything from your arms to the furniture to the laundry in the basket — is it because you skipped some puppy walks when the weather was bad? Do those behaviors come from early trauma that happened before you adopted them? Do genes deserve the blame for these issues?

Oh, how we all want the answers to these questions. I mean, what dog parents wouldn’t give just about anything to know what makes their dogs who they are? The short answer to the question about what makes dogs who they are is that there are a lot of factors, and the full answer is a long story about the many variables that influence who our dogs are and what they do.

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Dog DNA and Behavior: What It All Means

Scientific research continues to explore those variables, and a recent article in the journal Frontiers in Psychology points to the chemicals that are attached to the dog’s DNA as one factor that explains differences in behavior between dogs. That’s interesting because it is not the genes themselves (the dog’s genome) that the researchers looked at, but rather at the dogs’ “epigenome.”

The epigenome is the full set of modifications that regulate the expression and activity of genes, and that includes chemicals attached to their DNA. These chemicals are not the DNA (the dog’s genetics) itself. They are chemicals that are acquired by each dog during development and during their life, but not inherited from their parents. The unique set of chemical tags hanging on to each dog’s DNA makes up their epigenome, and it has a huge effect on the dog. In this study, researchers looked specifically at methylation, which involves the attachment of methyl groups (one carbon atom and three hydrogen atoms) to DNA. Interestingly, methylation can be affected by the environment, especially by pollution and toxins.

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Methylation may sound trivial, but it can influence all kinds of things, such as the production of neurotransmitters, metabolism of fats and other substances, eye and liver health, cellular energy, and detoxification — all of which can affect behavior. The reason for the strong influence on all kinds of physical and behavioral traits is that methylation affects which genes are “turned on and off” or expressed.

The Epigenetics of It All

So, while the epigenome is not the dog’s genes, the epigenome influences the expression of those genes. The association of variation in DNA methylation and behavioral traits suggests that differences in the expression of genes may contribute to certain canine behaviors. But this is not the same thing at all as the presence of certain genes being responsible.

Based on chemical analyses and surveys by pet parents in the current study, we know that methylation is associated with energy levels of dogs and on the fearful behavior they show towards strangers. There is still more research to be done on the additional aspects of behaviors that are affected by dogs’ epigenetics.

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Epigenetics has been described as the system by which experience influences the activities of our genes and also as the last nail in the coffin of genetic determinism. In other words, even though genes influence who dogs become, genes alone do not determine their behavior, and the genes do not trap them into a particular way of being.

The researchers summarize the importance of their research by writing: “In conclusion, we propose that energy and stranger-directed fear are partially predictable by DNA methylation in dogs. These behavioral associations are of interest because they provide evidence that changes in methylation can impact personalities, energy levels, and other aspects of behavior. Since methylation is dynamic and can be influenced by environmental factors, in the future we might be able to modify canine behavior by modulating these factors.”

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Science-speak aside, we all want to know why our dogs are who they are. Every dog is different in their personality, behavior, and temperament. Future studies of epigenetics may help us learn more about why dogs act as they do, allow us to screen dogs for suitability as service dogs or for temperament generally, and modify behavior by actively targeting methylation.

Karen B. London, PhD, CAAB, CPDT-KA

Karen B. London, Ph.D., is a Certified Applied Animal Behaviorist and Certified Professional Dog Trainer who specializes in working with dogs with serious behavioral issues, including aggression, and has also trained other animals including cats, birds, snakes, and insects. She writes the animal column for the Arizona Daily Sun and is an Adjunct Professor in the Department of Biological Sciences at Northern Arizona University. She is the author of six books about training and behavior, including her most recent, Treat Everyone Like a Dog: How a Dog Trainer’s World View Can Improve Your Life.