The nature-nurture debate: the relative importance of heredity and environment in determining behaviour; the interactionist approach.
& Nature-nurture (as an applied debate)
Essentially, the nature-nurture debate comprises two arguments: characteristics individuals are born with (and so are genetically predetermined and down to nature) and those which individuals learn from interaction with the environment (and so are down to nurture).
Nature refers to what we are born with, including any processes that develop as we mature, and any effects on ourselves as an organism before birth – these are genetically predetermined features. It is part of our biology and our evolution. Human beings are genetically programmed to look certain ways, behave in certain ways and die in certain ways. Our chromosomes are all similar, and our sex is determined by the non-autosomal chromosomes, either XX or XY. Our genes dictate the release of hormones, and these hormones dictate our human biology. Neurotransmitters also send messages around our brain and between neurones of the nervous systems. Our brains also play a part in our behaviours, for example, the amygdala is involved in generating emotions in the brain. Nurture refers to the effect of our environment and our experiences on us as we develop and grow. The biological environment that affects us before birth and after conception is still part of nature, but all other environmental influences are considered the ‘nurture’ side of the argument. Nurture is concerned with all external influences, such as family and peers. It is about learning through interaction and experiences with the environment, and socialisation processes.
Studying the debate
There are a number of methodologies used to study the nature-nurture debate:
- Twin studies – these can be used to easily identify what has a nature basis, and what has a nurture basis, by studying both monozygotic (identical) and dizygotic (non-identical) twins, as MZ twins share 100% of their DNA (whereas DZ twins only share half their genes). Using twin studies, we can identify genetic links between twins by looking at concordance rates to see to what extent certain characteristics have a biological basis. Interestingly, there is no characteristic which has a constant 100% concordance rate across all MZ twins (even though they share 100% of their genes), which suggests no matter how biological something may be, environment always plays an influential role
- Adoption studies – these studies work in the other way – we can use these to show the environmental influences on characteristics, and likewise where something is seen to not be affected by environment, we can suggest it is down to nature (for example, if a child is adopted and lives totally excluded from their genetic family, and his biological father has schizophrenia, and the child develops schizophrenia, we call this evidence that there is at least some biological cause for schizophrenia)
- Animal experiments – animals can be bred specifically that are 100% genetically-identical, and studies on these animals will show to what extent the environment has an effect on certain characteristics, as with twin studies
- Cross-cultural studies – these again can also help to show what characteristics in humans are innate and which are learned, for example, if attachment patterns between mothers and babies are the same across all cultures, then it might be concluded that human infants have an innate tendency to form an attachment with a caregiver (link into the debate of psychology and cultural differences)
The interactionist view
The nature-nurture debate is not clear-cut. For example, after conception, the womb is an environment that gives the foetus experiences (for example stimuli such as the mother smoking or drinking alcohol, and also noises heard from outside the womb). After birth, developmental (biological) maturation occurs, and so biological influences do not stop at birth. The interactionist view takes these elements into account. How approaches and applications answer the debate differs. Each of the approaches to psychology and applications of psychology from AS and A2 have theories, concepts and studies which approach the nature-nurture debate differently. They all have different views about the nature and nurture side of the argument, of course the two approaches with the heaviest weighting are the biological approach (nature) and the learning approach (nurture). The grid below describes how each approach and application answers the debate.