Nature versus Nurture

The phrase nature and nurture relates to the relative importance of an individual’s innate qualities (“nature” in the sense of nativism or innatism) as compared to an individual’s personal experiences (“nurture” in the sense of empiricism or behaviorism) in causing individual differences, especially in behavioral traits.

The alliterative expression “nature and nurture” in English has been in use since at least the Elizabethan period and goes back to medieval French. The combination of the two concepts as complementary is ancient.

The phrase in its modern sense was popularized by the English Victorian polymath Francis Galton, the modern founder of eugenics and behavioral genetics, in discussion of the influence of heredity and environment on social advancement.

The view that humans acquire all or almost all their behavioral traits from “nurture” was termed tabula rasa (“blank slate”) by John Locke in 1690. A “blank slate view” in human developmental psychology assuming that human behavioral traits develop almost exclusively from environmental influences, was widely held during much of the 20th century.

The debate between “blank-slate” denial of the influence of heritability, and the view admitting both environmental and heritable traits, has often been cast in terms of nature versus nurture.

These two conflicting approaches to human development were at the core of an ideological dispute over research agendas during the later half of the 20th century. As both “nature” and “nurture” factors were found to contribute substantially, often in an extricable manner, such views were seen as naive or outdated by most scholars of human development by the 2000s.

In their 2014 survey of scientists, many respondents wrote that the dichotomy of nature versus nurture has outlived its usefulness, and should be retired. The reason is that in many fields of research, close feedback loops have been found in which “nature” and “nurture” influence one another constantly.

As in the field of ecology and Behavioral Epigenetics, researchers think nurture make essential influence on nature. While in other fields, the dividing line between an inherited and an acquired trait becomes unclear.

HISTORY OF THE DEBATE

In the 20th century, this argument was in a way inverted, as some philosophers now argued that the evolutionary origins of human behavioral traits forces us to concede that there is no foundation for ethics.

In the early 20th century, there was an increased interest in the role of the environment, as a reaction to the strong focus on pure heredity in the wake of the triumphal success of Darwin’s theory of evolution.

SOCIAL SCIENCES

During this time, the social sciences developed as the project of studying the influence of culture in clean isolation from questions related to “biology”. Franz Boas’s The Mind of Primitive Man (1911) established a program that would dominate American anthropology for the next fifteen years.

In this study he established that in any given population, biology, language, material and symbolic culture, are autonomous; that each is an equally important dimension of human nature, but that no one of these dimensions is reducible to another.

The tool of twin studies was developed after World War I as an experimental setup intended to exclude all confounders based on inherited behavioral traits. Such studies are designed to decompose the variability of a given trait in a given population into a genetic and an environmental component.

John B. Watson in the 1920s and 1930s established the school of purist behaviorism that would become dominant over the following decades. Watson was convinced of the complete dominance of cultural influence over anything heritability might contribute.

These results did not in any way point to overwhelming contribution of heritable factors, with heritability typically ranging around 40% to 50%, so that the controversy may not be cast in terms of purist behaviorism vs. purist nativism.

Rather, it was purist behaviorism which was gradually replaced by the now-predominant view that both kinds of factors usually contribute to a given trait, anecdotally phrased by Donald Hebb as an answer to the question “which, nature or nurture, contributes more to personality?” by asking in response, “Which contributes more to the area of a rectangle, its length or its width?”

At the height of the controversy, during the 1970s to 1980s, the debate was highly ideologised. If biological determinism is a weapon in the struggle between classes, then the universities are weapons factories, and their teaching and research faculties are the engineers, designers, and production workers.”

HERITABLE TRAITS

The debate thus shifted away from whether heritable traits exist to whether it was politically or ethically permissible to admit their existence.

Heritability studies became much easier to perform, and hence much more numerous, with the advances of genetic studies during the 1990s. By the late 1990s, an overwhelming amount of evidence had accumulated that amounts to a refutation of the extreme forms of “blank-slatism” advocated by Watson or Montagu.

Pinker portrays the adherence to pure blank-slatism as an ideological dogma linked to two other dogmas found in the dominant view of human nature in the 20th century, which he termed “noble savage” (in the sense that people are born good and corrupted by bad influence) and “ghost in the machine” (in the sense that there is a human soul capable of moral choices completely detached from biology).

HERITABLE ESTIMATES

It is important to note that the term heritability refers only to the degree of genetic variation between people on a trait. It does not refer to the degree to which a trait of a particular individual is due to environmental or genetic factors. The traits of an individual are always a complex interweaving of both.

In contrast, the “heritability index” statistically quantifies the extent to which variation between individuals on a trait is due to variation in the genes those individuals carry. In animals where breeding and environments can be controlled experimentally, heritability can be determined relatively easily.

Such experiments would be unethical for human research. This problem can be overcome by finding existing populations of humans that reflect the experimental setting the researcher wishes to create.

One way to determine the contribution of genes and environment to a trait is to study twins. In one kind of study, identical twins reared apart are compared to randomly selected pairs of people.

The twins share identical genes, but different family environments. In another kind of twin study, identical twins reared together (who share family environment and genes) are compared to fraternal twins reared together (who also share family environment but only share half their genes).

INTERACTION OF GENES AND ENVIRONMENT

Heritability refers to the origins of differences between people. Individual development, even of highly heritable traits, such as eye color, depends on a range of environmental factors, from the other genes in the organism, to physical variables such as temperature, oxygen levels etc. during its development or ontogenesis.

The variability of trait can be meaningfully spoken of as being due in certain proportions to genetic differences (“nature”), or environments (“nurture”).

At the other extreme, traits such as native language are environmentally determined: linguists have found that any child (if capable of learning a language at all) can learn any human language with equal facility.

With virtually all biological and psychological traits, however, genes and environment work in concert, communicating back and forth to create the individual.

Extreme genetic or environmental conditions can predominate in rare circumstances, if a child is born mute due to a genetic mutation, it will not learn to speak any language regardless of the environment;

When traits are determined by a complex interaction of genotype and environment it is possible to measure the heritability of a trait within a population.

As an analogy, some laypeople may think of the degree of a trait being made up of two “buckets,” genes and environment, each able to hold a certain capacity of the trait. But even for intermediate heritabilities, a trait is always shaped by both genetic dispositions and the environments in which people develop,.

VARIABLES

One should also take into account the fact that the variables of heritability and environmentality are not precise and vary within a chosen population and across cultures. It would be more accurate to state that the degree of heritability and environmentality is measured in its reference to a particular phenotype in a chosen group of a population in a given period of time.

Some have pointed out that environmental inputs affect the expression of genes. This is one explanation of how environment can influence the extent to which a genetic disposition will actually manifest.

The interactions of genes with environment, called gene–environment interactions, are another component of the nature–nurture debate.

Yet another complication to the nature–nurture debate is the existence of gene-environment correlations. These correlations indicate that individuals with certain genotypes are more likely to find themselves in certain environments. Thus, it appears that genes can shape (the selection or creation of) environments.

HERITABILITY OF INTELLIGENCE

Evidence suggests that family environmental factors may have an effect upon childhood IQ, accounting for up to a quarter of the variance. normal child development requires a certain minimum level of responsible care.

Here, environment is playing a role in what is believed to be fully genetic (intelligence) but it was found that severely deprived, neglectful, or abusive environments have highly negative effects on many aspects of children’s intellect development.

PERSONALITY TRAITS

Personality is a frequently cited example of a heritable trait that has been studied in twins and adoptions. The most famous categorical organization of heritable personality traits were created by Goldberg (1990) in which he had college students rate their personalities on 1400 dimensions to begin, and then narrowed these down into “The Big Five” factors of personality—Openness, conscientiousness, extraversion, agreeableness, and neuroticism.

Payseur Family History
Fritz Springmeier – Bloodlines of Illuminati
The Rothschild Dynasty
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