Interactionist Approach

Q: Plomin et al. (1977)- Determining Nature and Nurture

__Plomin et al. (1977)__ identified three types of genotype-environment correlations: passive, reactive and active. These can complicate the degree to which we can determine nature and nurture influences.

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The Interactionist Approach - Interaction of Nature and Nurture

The nature perspective focuses on the innate genetic potential of an individual while the nurture perspective focuses on the impacts of the environment. Interactionism states that nature and nurture interact to form human personality.

Genotype and phenotype

There are two important definitions: genotype and phenotype.
- Genotype refers to the genes/DNA/alleles of a person.
  - The genotype is inherited from their biological parents.
- Phenotype refers to the physical or behavioural manifestation of the genotype.
  - For example, the genes that control eye colour are the genotype, whereas the actual eye colour is the phenotype.

Reaction range

Certain characteristics, like height, weight and intelligence have a reaction range (Gottesman, 1963).
This states that everyone has a genetic potential (genotype) for these characteristics.
But it is the environment that will determine to what extent the genotypic potential will be achieved.

Example 1 - height

For example, consider height.
People will have a genotype that will determine their height.
A person could have genes that will make them tall. But if they are raised in a household where there is poor nutrition, they may not end up as tall.
So both nature and nurture have an effect.

Example 2 - IQ

Another example would be IQ.
If a person is born in an area with little access to education, they will not develop in the same way as a person with the same intelligence genetic potential who has access to education.
This again shows the importance of both nature and nurture in combination.

The Interactionist Approach - Interaction of Nature and Nurture

Diathesis-stress model

Another example of interactionism is the diathesis-stress model.
- Diathesis refers to the genetic potential or vulnerability of a person developing a disorder.
- Stress refers to the environmental factors that may contribute.

Diathesis-stress model cont.

This model looks at the causes of psychological problems such as depression and schizophrenia.
People may have a genetic predisposition to these disorders (diathesis). But it may take an environmental cue (stress) to trigger the manifestation of the disorder.
So this is an example of nature and nurture being considered.

Imbalance of nature and nurture

There are certain scenarios where the balance is tipped more in favour of one side, be it nature or nurture.
For example, phenylketonuria (PKU) is a genetic metabolic disease where people can develop brain damage.
To prevent the worsening of the disease, people must eat certain proteins. So the environment (nurture) is a larger relative influence.

Plomin et al. (1977)- Determining Nature and Nurture

Plomin et al. (1977) identified three types of genotype-environment correlations: passive, reactive and active. These can complicate the degree to which we can determine nature and nurture influences.

Passive

Passive: people from the same families and raised in the same households have both similar genes and similar environment.
So it can be challenging to determine which has more of an influence.

Example - aggression in siblings

For example, in a study looking at aggression in siblings, the siblings would have similar genes and be raised in the same household.
So the aggression could be due to the genetics inherited from the parents or the influence of the aggressive parents.

Reactive

Reactive: a person’s experiences can be moulded by their genetics.
For example, the attractiveness of a person, generally determined by genetics, can affect how a person experiences life.
People usually act more positively towards attractive people; so attractive people’s environmental influences are more positive.

Active

Active: this is when people with certain genetic qualities actively seek out particular environments.
The environment, in turn, will also shape their behaviour.
This is referred to as reciprocal determinism (Bandura, 1986):
- Behaviour governs environment and environment governs behaviour.

Example - IQ and university

For example, those with inherited high IQ might actively seek out universities.
Consequently, the university environment would influence their tastes, behaviours, friendships and personality.