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The nature versus nurture debate is a long running issue in psychological research in which it is argued whether or not a person’s behaviour is motivated by their genetic inheritance (nature) or the way in which they learn from their environment (nurture). Although researchers in the past were adamant that behaviour had to be caused by one or the other, it is now largely agreed that most behaviour is caused by a combination of the two.
Nature
Research has long concluded that aspects of physical appearance are inherited – hair and eye colour. As well as this, general life expectancy and susceptibility to certain illnesses are also thought to be determined by a person’s nature. However, whether or not nature is responsible for human behaviour is much more difficult to ascertain.
It is thought that many aspects of behaviour may be innate to someone the minute they are born; in other words, their brain is already ‘wired’ for them to behave in certain ways.
Researchers who fully believe that all aspects of human development and behaviour are influenced by genetics and heredity, are known as nativists. They explain the fact that not all behavioural characteristics are seen at birth as part of physical maturation – that behaviours will appear when the person has physically matured enough to display them.
Nurture
At the opposite end of the nature versus nurture debate are environmentalists who believe that people are born as a completely blank slate, with no inherited factors that will affect their behaviour. They believe that all behaviour is determined by learning from the environment and the way in which a person is raised.
They do concede that certain aspects of development are, of course, biologically determined (such as puberty), but that the main reason why someone behaves in the way that they do is because of nurture.
How can research from psychological problems explain the nature versus nurture debate?
Caspi’s work shows that there is likely to be some form of influence by nature in determining psychological problems because it was found that short alleles appeared to increase someone’s susceptibility to becoming depressed. On the other hand, and in further support to the theory, it appeared that people with longer alleles were more resilient to stress.
Although the research could not conclusively prove that someone’s genetic make-up was responsible for whether or not they would experience some form of psychological problem, it does go some way in showing that a person’s genetic inheritance may well play a part.
Twin studies play a major part in determining if a psychological condition is due to genetics – as identical twins have identical DNA, it would stand to reason that if one twin had a condition then the other one would inherit it too. However, this is not always the case. As we have seen earlier in the unit, the concordance rate for this happening is almost never above 50%, which suggests that other factors, as well as genetics, must be involved. This makes it impossible to say, with any confidence, that the development of a psychological problem will be solely accountable for by a person’s genes.
On the other side of the debate, however, much research is continually being carried out to determine that, actually, someone’s environment and the way in which they are brought up are actually responsible for any form of psychological problem. What this means is that someone who is subject to negative experiences as they grow up are more likely to develop conditions such as depression and addiction.
For example, it is found that low-income parents, especially single mothers, are much more susceptible to depression than their higher paid counterparts. Furthermore, this can mean that the children who observe their parent displaying symptoms that characterise a certain type of mental illness, such as depression, may learn to behave in the same way and therefore, although it would seem that the child has the condition because their parent has it, they have not developed it through genetics but by observing and repeating the behaviour that they see on a regular basis.
The child may also develop a form of mental illness because their parent’s condition meant that they were not cared for sufficiently or did not form proper attachments; again, these could be environmental reasons as to why some conditions develop.
Individuals who are homeless are thought to be ten times more likely to experience depression than those people who are not. In 2015, 32% of people who were homeless reported that they experienced a mental health condition compared with just 25% of the general population.
Of course, this is not to say that single parents, their children or homeless people do not have some form of genetic heritability to a mental health condition, but the fact that the figures for mental illness within these populations is so high, does indicate that their environment (or nurture) is likely to play a part in why they have psychological problems
