Nature & Nurture: The Relative Importance of Heredity & Environment (AQA A Level Psychology)
Revision Note
Written by: Claire Neeson
Reviewed by: Lucy Vinson
The nature-nurture debate
The nature-nurture debate is probably the oldest debate in psychology and is based on the argument that either genes or environment determine behaviour
The nature side of the debate is based on the idea that heredity is key to human behaviour
Descartes (1596-1650) is an example of a nativist
He argued that all behaviour stems from innate, genetic sources
Locke (1632-1704) is an example of an empiricist
He argued that humans are born as 'blank slates'
Life, in effect, ‘writes’ on people to form behaviour based on external influences
The nurture side of the debate is based on the idea that environmental influences such as family life, peers, education, culture etc. are the key to understanding human behaviour
Nature
The nature side of the nature-nurture debate assumes that:
behaviour is innate i.e. people are born with a set of characteristics which are 'stamped' into them
behaviour is a product of genetic inheritance
behaviour can be understood by studying biological processes and structures such as hormones, neurotransmitters, regions of the brain
Taking a 'nature' approach to studying behaviour is likely to include one or more of the following methods:
Brain scanning e.g. fMRI, EEG
Concordance rates as used in twin studies
DNA analysis via urine or saliva samples
The heritability coefficient can be used to determine the extent to which phenotype is determined purely by genotype - or by other, external factors
Heritability is calculated as a figure ranging from 0 to 1
A value of 1 means that the behaviour/trait is purely genetic
A value of 0.5 means that half of the behaviour/trait is genetic and half is determined by environment
A value of 0.1 means that the behaviour/traits is not genetic and is determined by environment
The extreme nature argument suggests that some behaviours are entirely biologically based e.g.
women are born to be carers whereas men are born to be providers
Bowlby’s theory of attachment is an example of a pro-nature argument as he based his ideas on the work of ethologists such as Lorenz, concluding that attachment is an essential evolutionary mechanism needed for the survival of the species
Evaluation of nature
Strengths
Understanding genetic inheritance has helped to identify atypical chromosome patterns as seen in conditions such as Klinefelter’s syndrome
This is a clear indication of a biological basis to behaviour as the condition is not determined by environmental influence
Therefore the nature side of the debate can be evidenced using clinical data
The discovery of the nAChR nicotinic receptor in the brain is compelling evidence for a pro-nature explanation of nicotine addiction
Limitations
Using a purely nature-based approach can result in prejudiced, overly deterministic, and possibly dangerous assumptions being made about people based on their gender, ethnicity, sexuality etc.
The controversial book, 'The Bell Curve' (1994) by Herrnstein and Murray sets out an overtly biased, political agenda which makes claims as to the genetic basis of IQ which are highly offensive and have no basis in empirical evidence
Twin studies have failed to show 100% concordance between MZ (identical) twins across a range of studies e.g.
McGuffin et al. (1996) found that MZ twins showed a 46% concordance rate for depression compared to 20% in DZ (non-identical) twins
Gottesman (1991) found a 48% concordance rate for schizophrenia in MZ twins and a 17% concordance rate in DZ twins
As MZ twins share exactly the same DNA then the concordance rate should reflect this (and as it does not then environment must play a role in behaviour as well)
Nurture
The nurture side of the nature-nurture debate assumes that:
behaviour is learned
behaviour is a product of environmental factors e.g.
upbringing
family and peer relationships
schooling
experience
learning occurs via conditioning based on environmental forces/stimuli
Research which is relevant to nurture includes
classical conditioning and operant conditioning as part of behaviourism
conformity to social roles as in the Stanford Prison experiment
field studies such as Schaffer & Emmerson (1964)
The extreme nurture view suggests that humans are born as Locke's ‘blank slate’ (the basis of hard determinism), ready to be ‘written on’ by life experiences
The learning theory of gambling addiction is an example of a pro-nurture argument
It is based on the idea that the gambler is positively reinforced in their gambling behaviour
This is strengthened every time they gamble, even if they lose money
The learning theory of attachment is known as 'cupboard love' theory
This assumes that babies attach to whoever feeds them
The person who feeds them changes from the neutral stimulus to the conditioned stimulus as they become associated with food which is the unconditioned stimulus
Evaluation of nurture
Strengths
The argument that nurture is a key influence on behaviour is evidenced by the two-process model of phobias
This model demonstrates phobias as being learned via classical conditioning
An aversive experience (e.g. a dog bite as a child) changes a neutral stimulus (the dog that bit you) into a conditioned phobic stimulus (dogs in general)
The phobia is reinforced via operant conditioning
Every time you see a dog you feel high anxiety, fear, panic etc. which only ceases when the dog is out of sight
Twin studies - which are conducted to investigate a biological (nature) basis to behaviour - tend to (conversely) support a nature argument as well
Such studies fail to find 100% concordance between MZ twins
Concordance rates of around 50% suggest that upbringing and experience share equal importance with genetics in forming behaviour
This bolsters the argument that environment is a key influence on behaviour as twins are (usually) reared in the same household
Limitations
Although twin studies do not show a 100% concordance rate they are still strong indicators that some behaviours may have a genetic basis e.g.
Nan et al. (2012) found a 61%-80% concordance rate for obesity in a sample of 8000 MZ twins
The nurture side of the debate cannot account for individual differences within children raised in the same family environment
One child may turn to crime while the other child never breaks the law
One child may develop a drug addiction while the other child does not
Examiner Tips and Tricks
Examiners have commented that students lose marks because they refer to only one side of a debate in their responses. This is particularly true of the nature-nurture debate with some student responses referring to the ‘nature debate’ or the ‘nurture debate’ which does not make sense (and examiners don’t like it - and you want to please the examiner!)
You should refer to the ‘nature/nurture side of the debate’ in your exam answers as stating it this way acknowledges that a debate is made up of two opposing arguments. You could also use expressions such as ‘the pro-nurture argument’ or ‘a nature-based approach’ as well.
The interactionist approach
The interactionist approach is used by most psychologists today when considering the impact of nature-nurture on an individual
Nature does not trump nurture (and vice-versa)
Nature and nurture interact with each other; one cannot exist without the other
A genetic predisposition can be moderated or even ‘switched on’ by the environment as seen in the diathesis-stress model e.g.
Someone who is born with (nature) a predisposition to depression is likely to have their depression 'switched on' by environmental factors (nurture) such as a bereavement or relationship breakdown
'Diathesis' means 'vulnerability'
The 'stress' aspect of the model is the result of encountering an environmental trigger such as those outline above
A genetic predisposition can be moderated or even ‘switched on’ by the environment as seen in the theory of epigenetics
This refers to how environmental factors can change gene expression
Epigenetic changes do not alter the DNA sequence but they can encourage or suppress specific genes from being expressed e.g.
a pregnant woman who undergoes starvation during wartime finds that the baby goes on to be an obese adult compared to her other children
epigenetic changes wrought by starvation during pregnancy changed the expression of genes coding for fat storage in her developing child (Tobi et al. 2018)
Evaluation of the interactionist approach
Strengths
An interactionist approach is more holistic than an extreme nature or nurture approach as it acknowledges the complex relationship between biology, psychology and environment
This is a more valid explanation of behaviour than just nature or nurture alone
Constructivism (sometimes referred to as ‘niche-picking’) is based on interactivist ideas with its emphasis on people picking environments suited to their natural likes, dislikes, habits and talents e.g.
a child who is naturally musically gifted is likely to seek out opportunities to listen to music, play music or be with other musicians
This is a strength because it demonstrates that nature and nurture are aligned with each other
Because the interactionist approach acknowledges the role of both nature and nurture in behaviour it does not really have any limitations
Worked Example
Here is an example of a question you might be asked on this topic which includes AO1, AO2 and AO3.
AO1: You need to demonstrate knowledge and understanding of key concepts, ideas, theories and research.
AO2: You need to apply your knowledge and understanding, usually referring to the ‘stem’ in order to do so (the stem is the example given before the question).
AO3: You need to analyse and evaluate key concepts, ideas, theories and research.
Q. Discuss one or more features of the nature-nurture debate. Refer to at least one theory/study/topic you are familiar with in your answer
[8 marks]
AO1 = 3 marks, AO2 = 2 marks, AO3 = 3 marks
Model answer:
AO1: Outline key features of the nature-nurture debate:
The nature-nurture debate represents a dichotomy in the explanation of human behaviour: what is innate and what is learned; [1 mark]
Nativists such as Descartes argued that all behaviour stems from innate, genetic sources whereas empiricists such as Locke argued that human beings are born as blank slates, with life ‘writing’ on them; [1 mark]
AO2: Refer to at least one theory/study/topic:
The biological approach tends to favour a nature-based interpretation using studies of genetics (e.g. twin studies) to argue that there is a strong inherited component to some behaviours.; [1 mark]
Behaviourism is aligned with a nurture-based approach, with behaviour being viewed through the prism of environmental stimuli acting upon and informing behaviour (e.g. Pavlov’s experiments with dogs); [1 mark]
AO3: Select key evaluation points:
Each side of the debate can tend to be overly reductionist and deterministic (e.g.genes determine criminality/upbringing determines criminality) which results in overly biased and one-sided explanations; [1 mark]
Twin studies could be used as an argument for both nature and nurture as concordance rates are higher for MZ twins (nature) but never 100% so the environment (nurture) clearly plays a role; [1 mark]
It is more difficult to operationalise and measure topics that fall under the 'nurture' side of the debate e.g. the effect of an abusive childhood on future relationship behaviours whereas nature-type topics are more easily measured e.g. an MRI scan to determine the site of brain damage linked to amnesia. [1 mark]
Neither a purely nature or nurture argument is complete in itself and modern thinking is that an interactionist approach provides the most complete explanation of behaviour as seen for example via the diathesis-stress model; [1 mark]
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