It seem one can distinguish three different kinds of genetic determinism of common patterns of human behavior:

  • behavior that is directly wired into our nervous system, e.g. face-related mirror neurons and chewing,
  • behavior that is within reach of operand conditioning, i.e. that is predisposed by certain features of our bodies (and environment) and relatively easily discoverable by exploration, e.g. how to throw something,
  • behavior that is passed on culturally, e.g. tool use.

Does there exist something like this in the literature?

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    $\begingroup$ The standard is to group any phenotypic variance such as variance in behaviour in a population as being caused by environmental or genetic variance. I don't have a good understanding about the difference between your two first points. Brain is a predisposed feature of our bodies causing a behaviour. $\endgroup$
    – Remi.b
    Jul 26, 2015 at 19:52
  • $\begingroup$ I think the nature-nurture issue of human behavior is one on which libraries can be filled. Moreover, this question, if 'schema' refers to "organized pattern of thought or behavior that organizes categories of information and the relationships among them" en.wikipedia.org/wiki/Schema_(psychology) this Q is better suited for CogSci.SE. However, even there it will likely be closed given the vastness of the topic. I vote to close here. You may, or may have more luck at CogSci. $\endgroup$
    – AliceD
    Jul 28, 2015 at 4:37

1 Answer 1


We can only observe correlations

Let's just talk about statistics. You can see a correlation between two things only if there is variation for these two things. It therefore, make no sense to look at a single trait that has no variance and ask "is it genetically coded?". The only thing that makes sense is to understand what variables explain the observed variance for the trait of interest. Here, in your question, you are interested in behavioural traits. This answer stands for behavioural traits as it stands for any other phenotypic traits.

What variables could explain variance in a given trait?

To make it easy, let's consider only two variables, genetics and environment. In reality, one should consider other variables such as epigenetic for example. The total variance in phenotype that you observe is the result of the addition of the variance of this phenotype that is due to genetics variance ($V_G$) and the variance of this phenotype that is due to environmental variance ($V_E$) and their covariance ($COV_{GE}$). In other words:


It is very common to express the phenotypic variance as being the sum of the genetic and environmental variances (and some others such as epigenetic variance). However, you are free to make this partitioning as you feel it useful for you.

Let's investigate those variables a bit further

Of course, $V_E$ and $V_G$ can be further decoupled into a sum of variances (and covariances). And you are free to do the decoupling exactly as you want to. For example $V_E$ could be defined as the sum of the phenotypic variance that is due to variance in temperature ($V_T$), the phenotypic variance that is due to variance in water availability ($V_W$) and the phenotypic variance that is due to variance in the culture of the parents ($V_P$) (and all the covariance). $V_E = V_T + V_W + V_P + ... $

Similarly, the genetic variance $V_G$ can be further decoupled. It is standard to decouple this variance in dominance vs additive effects (relating to the genetic architecture underlying the trait) but this won't be of great help to you. How about talking about variance in the genes affecting brain morphology $V_B$ and variance in the genes affecting hormones concentration $V_H$ and their covariance (epistasis and pleiotropy) $V_G = V_B + V_H + ...$.

Common schema

To my knowledge there is no common schema in how to partition those variances for the specific study of the mechanistic of behaviour. I don't really understand what is the partitioning that you're suggesting in your post but I am hoping that this answer can help you to think further and eventually come up with a satisfying schema.

  • $\begingroup$ Thank you for this beautiful answer; it helped me to grasp some key concepts. It's quite difficult to understand my schema in terms of generic variance. It seems that it successively plays a less immediate role: Behaviors in (1) are presumably highly correlated with certain genes, in (2) there is more a dependence on the environment and in (3) the behavior depends on embodiment and situatedness. $\endgroup$
    – Lenar Hoyt
    Aug 2, 2015 at 23:46
  • $\begingroup$ The code for a fit phenotype is successively outsourced from genetics to memetics. The genetic code still facilitates the common behavioral patterns, but doesn't fully specify those in the latter groups since they require both an environmental and even a sociocultural context in the case of (3). Behaviors in this category are rather developed over generations, while those in (2) are discoverable within a lifetime (mostly before adulthood). $\endgroup$
    – Lenar Hoyt
    Aug 2, 2015 at 23:47

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