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breeding·March 18, 2026·14 min read

Temperament and Selection: Why Temperament Is the First Filter

How Just Behaving evaluates temperament from puppyhood through adulthood, what heritability actually means for your puppy, why puppy temperament tests aren't destiny, and why the dog's ability to live calmly inside a family is the quality that matters most.

Preamble: Why Temperament Comes First

Walk into most breeding programs and you'll find the organizational logic clear: health first, then structure, then temperament as a nice-to-have. It's the hierarchy the dog show world has settled on for decades. Just Behaving inverts this.

We lead with temperament. Not because health doesn't matter-it's non-negotiable. We invest heavily in orthopedic screening, cardiac evaluation, eye clearance, and genetic testing. Every dog in our breeding program has earned these credentials. But here's what we've learned: a dog can have perfect hips, clear cardiac evaluations, excellent eyes, and clean genetic panels and still not belong in a breeding program if its temperament isn't right.

This might sound subjective-like we're talking about something soft or preference-based. We're not. Temperament has a measurable heritable component. [Documented - Canis familiaris] It can be evaluated rigorously, tracked systematically, and selected for across generations. The science is more complex and more honest about its limitations than most breeding programs acknowledge, but it's as real and as valid as hip scores or cardiac measurements.

Here's the deeper logic: the Five Pillars of Just Behaving-mentorship, calmness, structured leadership, prevention, and indirect correction-describe how we raise puppies. But these are not training techniques imposed onto the puppy. They're natural behaviors that emerge when a puppy has the right biological starting point. We're not trying to force a fearful, hyperaroused, or socially withdrawn dog into a mentorship framework. We're selecting for puppies whose temperament creates the conditions where these pillars can unfold naturally.

Selecting for temperament isn't separate from raising philosophy. It is its biological prerequisite.

Chapter 1: What Temperament Actually Is

When we talk about temperament, we mean something specific and measurable: the consistent individual differences in behavioral and emotional reactivity, and the self-regulation of that reactivity, that have a biological basis and appear early in development. [Documented - Canis familiaris] This is different from the colloquial notion of "personality." We're talking about observable, repeatable patterns that persist across time and contexts.

These patterns cluster into dimensions that researchers have identified across dog populations (Jones & Gosling, 2005; Svartberg et al., 2005). [Documented - Canis familiaris] Think of them as fundamental axes along which dogs vary:

These dimensions exist on a spectrum. There's no "right" answer to any of them in the abstract. But for a dog that will live as a family member within the Just Behaving raising framework, certain positions on these dimensions work better than others.

What the Numbers Tell Us

When behavioral geneticists measure heritability-the proportion of variation in a trait that stems from genetic differences rather than environmental differences-they express it as h², a number between 0 and 1. A heritability of 0.40 means that roughly 40 percent of the individual differences you see in a population for that trait are due to genetic variation; the other 60 percent comes from differences in experience, environment, and life history. [Documented - Canis familiaris] This is important: high heritability does not mean "genetically determined" or "unchangeable." It means genes matter in this population in these conditions.

For Golden Retrievers specifically, recent research using the BPH (Behavioral Personality and Heritability) framework provides our best estimates. In a study of approximately 1,535 Golden Retrievers, Strandberg and colleagues (2025) found these narrow-sense heritability estimates: [Documented - Canis familiaris - Golden Retriever]

These numbers tell us that for Golden Retrievers, heritable variation explains somewhere between 10 and 30 percent of the differences you see among individual dogs in these traits. That's significant. It means selection can work. But it also means environment, experience, and individual life history matter enormously.

For fear and anxiety phenotypes more broadly, heritability estimates cluster around 0.10-0.30. [Documented - Canis familiaris] Trainability-the dog's inclination to respond to structured guidance-tends to show somewhat higher heritability in working-dog populations, though this varies by measurement method and context. [Documented - Canis familiaris]

A crucial caveat: most of these behavioral genetics datasets come from structured working-dog populations-guide dogs, assistance dogs, search-and-rescue dogs, military dogs. These are dogs raised in intensive, standardized training environments with sophisticated assessment protocols. Extrapolating from these numbers to companion-dog breeding is partially valid (the biological mechanisms are the same) but context-dependent. A trait that shows high heritability in a cohort of guide dog candidates might show different heritability in a pet dog population with vastly more varied raising environments. [Documented - Canis familiaris] We have to be honest about this limitation.

What This Means for Your Family

The key translation: temperament is partly genetic and partly environmental. Selection matters. Raising matters. Both are true simultaneously, and neither erases the other.

When Just Behaving selects for temperament, we're working on the genetic half. We're choosing breeding dogs that display calm confidence, natural sociability, moderate excitability, and the capacity to regulate their own arousal. We're not guaranteeing that every puppy will inherit these traits completely; inheritance is probabilistic, not deterministic. But we're shifting the odds-raising the average, narrowing the range of extremes.

The environmental half is then your responsibility as a raising family. A puppy born with a genetic predisposition toward calmness who lands in a chaotic, high-arousal household might never develop that calm potential. Conversely, thoughtful, consistent raising can help a puppy with a mild genetic lean toward reactivity learn better self-regulation than its raw temperament might suggest. [Documented - Canis familiaris] (We'll talk more about this in the context of the Five Pillars.)

This is why we say: temperament selection is not deterministic. It's probabilistic. It creates conditions. Your job is to honor those conditions by raising calmly, consistently, and with structured leadership.

Chapter 2: The Genetics Are Polygenic-No Single "Temperament Gene"

This is where honest science gets complicated, and we think it's important to walk through the complication.

There is no "temperament gene." Temperament traits are polygenic, meaning they're influenced by hundreds-possibly thousands-of genetic variants, each contributing a small effect. [Documented - Canis familiaris] This has several important consequences.

First: there's no DNA test for "good temperament." A blood test cannot tell you whether a puppy will grow into a calm, confident, trainable adult. Some researchers and commercial testing companies have suggested otherwise, but the actual effect sizes from whole-genome association studies (GWAS) remain small and difficult to replicate across populations. [Documented - Canis familiaris] Ilska and colleagues (2017) identified candidate genomic regions associated with behavioral traits in dogs, but the variance explained by these identified loci remains modest. Morrill and colleagues (2022) published a landmark study in Science finding that breed-which you might expect to be a strong genetic predictor of behavior-explains only about 9 percent of behavioral variation in individual dogs. [Documented - Canis familiaris] If breed accounts for that little variation, you can imagine how small individual genetic variants are.

The practical implication: phenotypic evaluation-observing the actual behavior of actual dogs over time in varied contexts-remains the most reliable tool we have. [Heuristic - Canis familiaris] Genomic prediction for behavioral traits is not yet operationally useful for breeders. We're decades away from DNA tests that can meaningfully predict temperament.

Second: because temperament is polygenic, selection works through gradual, population-level shifts across generations. You cannot breed one generation and see dramatic change. Good temperament selection is a long, patient process of consistent choices. This is why Just Behaving keeps detailed records going back years, tracks offspring outcomes, and maintains contact with families. We're not looking for quick wins. We're building a population that trends toward calm, confident, socially intelligent dogs.

Third: gene-by-environment interactions are significant. The same genetic predisposition can produce different outcomes depending on the raising environment. A puppy genetically inclined toward confidence raised in a terrifying environment might develop fear behaviors. A puppy with a mild genetic tendency toward fearfulness raised in a safe, calm, well-structured environment might become notably resilient. [Documented - Canis familiaris] Genes don't mandate outcomes; they create tendencies within which environment operates.

This complexity is why Just Behaving invests in both genetic selection and raising methodology. We select for good temperament genes. Then we raise in a way that honors and develops that genetic potential.

Chapter 3: Puppy Temperament Testing-What It Can and Cannot Tell You

This section is important because many breeders and puppy-buying guides tout early puppy testing as a crystal ball. It's not. Let's be honest about what the science actually shows.

Many breeders use structured assessments at around 7 or 8 weeks of age-tests like the Volhard Puppy Aptitude Test, the Puppy Behavior Assessment, or various iterations inspired by these. These tests typically involve presenting the puppy with specific stimuli (novel objects, sounds, unfamiliar people, handling) and scoring their response on predetermined scales. There's an appealing logic to this: catch puppies at 7 weeks, predict what they'll be like at 7 years, match them correctly to families from the start.

The research reality is more nuanced.

Predictive validity-the statistical strength of the link between 7-week test scores and adult behavioral outcomes-is generally low to moderate across studies. [Documented - Canis familiaris] Wilsson and Sundgren (1998), in a frequently cited longitudinal study, tested puppies at 8 weeks using the Campbell Puppy Aptitude Test and assessed the same dogs again at 18 months with a standardized adult behavior test. They found limited correspondence between puppy test scores and adult behavior patterns. [Documented - Canis familiaris] Foyer and colleagues (2014) examined puppy tests and validity and found similar limitations in predictive power. [Documented - Canis familiaris] Bray and colleagues (2019), studying guide dog candidates from a major service dog organization, found that early puppy assessments explained only a modest proportion of the variance in adult working outcomes. [Documented - Canis familiaris] Even more striking: inter-rater reliability (whether different people scoring the same puppy produce similar scores) and test-retest reliability (whether a puppy produces similar scores if tested twice within days) are often lower than breeders assume. [Documented - Canis familiaris]

Why? A 7-week-old puppy is a tiny being operating in a developmental window where behavior is incredibly state-dependent. Is it hungry? Tired? Overstimulated? Socialized to the test environment or encountering it for the first time? The behavior you observe at that moment is influenced by immediate physical state, recent experience, and the emotional tone of whoever is administering the test. [Documented - Canis familiaris] A perfectly calm, confident puppy in the wrong immediate state might look fearful. A naturally bold puppy in an unfamiliar environment might look reserved. The test captures a slice of behavior, not destiny.

There's also measurement instrument variability. Different puppy tests use different protocols, different scoring systems, different interpretation frameworks. A score that "predicts high trainability" on one test might mean something entirely different on another. This lack of standardization limits the scientific power of puppy testing as a field.

How Just Behaving Handles Puppy Temperament Assessment

We conduct a structured Puppy Aptitude Test at approximately 49 days (7 weeks) of age, informed by the Volhard framework and supplemented with additional assessments. We value the data. We score it carefully. We video record the testing. We use it for matching puppies with families and for building a longitudinal record of behavioral development.

But we do not treat the 7-week snapshot as a destiny prediction.

Here's how we think about it: the test provides a baseline behavioral profile. It gives us early information about how the puppy is responding to novelty, handling, social interaction, and mild stress. That's useful. It can help us identify outliers-a puppy who shows extreme fear or extreme aggression at 7 weeks warrants attention and careful family matching. It can help us notice which puppies gravitate toward boldness or which show early signs of strong retrieving drive.

But it's one data point in a lifelong evaluation, not the final word.

A puppy's behavior will change significantly between 7 weeks and 12 months. It will change again during adolescence. It will continue changing as the adult dog settles into its household and develops confidence or anxiety based on its experiences. The 7-week test can't account for any of that. It's a photograph, not a prediction.

For families: be skeptical of any breeder who says, "At 7 weeks, I could tell this puppy would be calm and friendly as an adult." That claim overstates the evidence. Be equally skeptical of a breeder who doesn't evaluate puppies for temperament at all; that suggests they're not thinking systematically about behavioral development. Honest breeders are in between: we test because it's useful. We report what we see. And we acknowledge that puppies change.

Chapter 4: How Just Behaving Evaluates Temperament Across the Dog's Life

Puppy testing is one tool. It's not the whole picture. Just Behaving's temperament evaluation is longitudinal and multi-stage, spanning from birth through the dog's entire life-and for breeding animals, through evaluation of their offspring.

Stage 1: Neonatal and Early Socialization Observation (Birth to 7 Weeks)

We observe puppies from the moment they become mobile. Which puppies explore first? Which are bolder in approaching novel stimuli? How do littermates interact-who initiates play, who defers, who moderates? Do we see any early signs of extreme fear responses, aggression, or social withdrawal?

This observation is informal in the sense that we're not always scoring on a formal scale. But it's deliberate. We're watching. We're taking notes. We're building a sense of each puppy's emerging personality. A puppy that seems fearful of handling at 3 weeks, confident in exploring at 5 weeks, and naturally drawn to littermates throughout often develops into a dog with good confidence and social engagement. A puppy that seems withdrawn or defensive from early weeks often maintains those traits, though raising can modulate their expression.

Stage 2: Structured Puppy Aptitude Assessment (~49 Days)

At approximately 7 weeks, we conduct a formal puppy assessment. The test occurs in an unfamiliar location, administered by someone who is not the puppy's primary caretaker. This removes some environmental familiarity and tests the puppy's response to a new person, new place, and novel stimuli.

The assessment evaluates multiple behavioral dimensions:

Each sub-test is scored on a simple scale and video recorded. We maintain detailed notes on each puppy's responses. This creates a permanent record that we can track across time and correlate with later behavioral outcomes in the individual dog and, when relevant, in its offspring.

Stage 3: Ongoing Behavioral Tracking Through Development (7 Weeks to Maturity)

As puppies transition from breeder care to family homes, behavioral development continues. We maintain regular contact with families and track how puppies are developing:

We also track program dogs that remain in the Just Behaving facility through adolescence and into adulthood. Behavioral development is most visible and most critical during this period. A puppy that seemed reasonably calm at 7 weeks might become hyperaroused during adolescence, or conversely, a slightly reserved puppy might develop into a confident, settled adult as its brain continues maturing.

Stage 4: Adult Evaluation for Breeding Candidacy

Temperament is the first filter for breeding candidacy. A dog must demonstrate:

Any dog that doesn't meet these criteria does not enter the breeding program, regardless of health clearances, pedigree, or show wins.

Stage 5: Offspring Tracking and Feedback Loop

Just Behaving maintains lifelong contact with families who receive our puppies. We track behavioral outcomes through the dog's entire life. When we see patterns-certain breeding pairs consistently producing puppies that develop into calm, confident, resilient adults-that informs our decisions. When we notice trends in the opposite direction, we adjust breeding plans or discontinue pairings.

This is slow, patient work. It takes years to see whether a breeding decision produced good results. But it's the only way to know whether our selection criteria are actually working.

The JBBRI: A Quantitative Measure

Just Behaving has developed an internal behavioral assessment tool called the JBBRI (Just Behaving Behavioral Risk Index). [Observed - internal data, independent validation pending] This tool allows us to track behavioral characteristics across dogs in our program, identify patterns, and quantify the population-level shift in temperament traits over generations.

The JBBRI is based on behavioral observations, assessment data, and structured evaluation across multiple domains. It's not a DNA test. It's a holistic measure that captures the real behavioral phenotype of each dog. We use it to track our own progress and to be accountable to our selection criteria.

Chapter 5: Temperament and the Five Pillars

This is where temperament selection and raising philosophy come together.

The Five Pillars describe how puppies develop best when surrounded by calm, structured mentorship:

These Pillars work best when they encounter a receptive biological substrate.

Consider a puppy born with extreme fear reactivity-the kind that doesn't resolve through normal exposure and socialization. This puppy has a narrower window of tolerance. The Pillars can still apply, but the window in which they operate is smaller, more fragile. The puppy's nervous system is working against the raising framework, not with it.

Similarly, a puppy born with extremely high arousal that resists regulation, or one with very low social engagement-these puppies have temperamental predispositions that make it harder for the Pillars to unfold naturally. Not impossible. Harder. Less predictable.

This is why temperament is the first filter in breeding selection. Not because imperfect dogs don't deserve good lives-every dog does. But because a breeding program has a specific responsibility: to produce puppies whose biological predispositions align with the raising methodology that families are asked to follow.

When you receive a Just Behaving puppy, the puppy already has a temperamental substrate that wants to be calm, that wants to be mentored, that wants to follow structured leadership. Your job is to honor that predisposition through consistent, calm raising. You're not fighting the puppy's nature. You're developing it.

This is perhaps clearest in the context of mentorship. Adult dogs in the raising environment serve as mentors and models for young puppies. For this to work, the adult must naturally embody calm, settled behavior. An anxious, reactive, socially chaotic adult dog cannot mentor a puppy toward emotional regulation. It can't teach what it doesn't have.

By selecting breeding dogs that are naturally calm and confident, we ensure that the adult mentors in the environment have genuine calm to share. Temperament selection directly determines the quality of the mentoring environment. They're not separate. They're the same commitment viewed from different angles.

Chapter 6: What Families Should Know

If you're considering bringing a Just Behaving puppy into your home, here's what matters most:

Temperament is partly genetic and partly environmental. Neither erases the other. Breeder selection shifts the genetic odds. Your raising approach shapes how that genetic potential develops. Both matter. If someone tells you "it's all genetics" or "it's all how you raise them," they're oversimplifying.

Ask your breeder how they evaluate temperament. If the answer is "we just know our dogs," that might reflect genuine decades of experience. But it might also reflect a lack of systematic thinking. Better breeders are honest about their methods: we do puppy assessments, we track outcomes, we maintain feedback loops, we adjust breeding decisions based on what we learn. If a breeder can't articulate their selection criteria, that's a yellow flag.

Your 8-week-old puppy is not your 2-year-old dog. The temperament assessment at 7 weeks is useful information, not destiny. Puppies change. A mildly reserved puppy often becomes confident through good raising. A boldly exuberant puppy often settles through consistent structure. The early snapshot is real and useful. It's just not the whole story.

Consistency, calmness, and structured leadership during critical windows shape who the puppy becomes. The raising part is genuinely important. A puppy born with excellent genetic predispositions can fail to develop well in a chaotic environment. Conversely, thoughtful raising can help a puppy with milder genetic predispositions develop beyond what raw numbers might suggest. You're not passive observers of your puppy's temperament. You're actively shaping it through the raising environment you create.

The breeder's job is to select for the right starting point. Your job is to honor that starting point through consistent, calm, structured raising. When a breeder selects for temperament first, they're saying: "I've chosen this dog because its nature aligns with calm, mentoring-based raising. Your job is to provide that environment."

Works Cited

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Duffy, D. L., & Serpell, J. A. (2012). Predictive validity of a method for evaluating temperament in young guide and service dogs. Applied Animal Behaviour Science, 138(1-2), 99-109. DOI: 10.1016/j.applanim.2012.02.011

Foyer, P., Bjellerup, A., Odenmark, M., & Jensen, P. (2014). Behavioural development in dogs and validity of puppy tests. Applied Animal Behaviour Science, 158, 90-97.

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Strandberg, E., Nilsson, K., & Svartberg, K. (2025). Genetic parameters of personality traits in dogs based on behavioral assessment and questionnaire information. Applied Animal Behaviour Science, 286, 106619. DOI: 10.1016/j.applanim.2025.106619

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Dan RoachJust Behaving Golden Retrievers