The nature-nurture debate

• What is the nature-nurture debate?


  Concerned with the extent to which aspects of behaviour are a product of inherited or acquired characteristics.
• What is the environment?


  Everything that is outside our body, including people, events and the physical world. Any influence on behaviour which is non-genetic.
• Lerner identified different 'levels' of the environment, which ranged from pre-natal experiences to post-natal experiences. The view that the mind is a 'blank skate upon which experience writes upon' is typical of a behaviourist approach.
• What is nature?


  Any influence on behaviour which is genetic eg. the action of genes.
• What is heredity?


  The process by which traits are passed from parents to their offspring. referring to genetic inheritace. The heritability coefficient can be used to quantify the extent to which a characteristic has a genetic basis.
• What is the interactionist approach?


  The idea that nature and nurture are linked to such an extent that it does not make sense to seperate the two, so researchers instead study how they interact and influence each other.
• Example of the influence of nature:

  The concordance rate for schizophrenia is 40% for MZ twins and 7% for DZ twins. This illustrates how nature plays a part in contribution to the disorder. However, concordance rates for MZ twins are not 100%, despite being genetically identical. This suggests that nurture and the environment also plays a significant role in development.
• Example of the influence of nurture:

  Behaviourists assume that all behaviour can be explained in terms of experience alone. Skinner used to concepts of classical and operant conditioning to explain learning and suggests that attachment could be explained in terms of classical conditioning where the food reduces the discomfort of hunger and is therefore rewarding.
• What is the diathesis-stress model?

  The diathesis-stress model suggests that psychopathology is caused by a biological/genetic vulnerability (the diathesis) which is only expressed when coupled with a biological or environmental 'trigger' (the stressor). Tienari et al. (2004) found that in a group of Finnish adoptees those most likely to develop schizophrenia had biological relatives with a history of the disorder and had relationships with their adoptive families that were defined as 'dysfunctional'.
• Interactionism - Epigenetics:


  Epigenetics is a change in genetic activity without changing the genetic code. Lifestyle and events we encounter (eg. smoking) leave epigenetic 'marks' on our DNA - these marks tell our bodies which genes to ignore and which to use, and may influence the genetic code of our children. So epigenetics introduces a third element into the nature-nurture debate - the life experience of previous generations.
• AO3 - Understanding the interaction may have real-world implications:

  Extreme beliefs in the influence of nature or nurture may have implications for how we view human behaviour. Nativists suggest genes determine and characteristics ('anatomy is destiny'). This has led to controversy (eg. linking race to eugenics policies, and advocating a model of society that manipulates its citizens). Recognising that human behaviour is both nature and nurture is a more reasonable way to approach the study and 'management' of human behaviour.
• AO3 - Confounding factors of unshared environments:


  Research that tries to 'tease out' environmental influences is complicated by the fact that even siblings raised within the same family will not have identical upbringings - there are 'shared' and 'unshared' environments. Dunn and Plomin (1990) suggest individual differences means siblings may experience life events differently (eg. age leads to a life event such as parental divorce having a different meaning to each sibling). This would explain the finding that even MZ twins reared together do not show perfect concordance rates.
• AO3 - Gene-environment interactions explained by constructivism:


  People create their own nurture by actively selecting environments appropriate for their nature. This two-way interaction between nature and nurture is known as constructivism. A naturally aggressive child is more comfortable around similar children and 'chooses' their environment accordingly. This environment then affects their development. Plomin (1994) calls this 'niche-picking' and 'niche-building'. Constructivism shows it is impossible and illegal to try to separate nature and nurture influences on a child's behaviour.
• AO3 - Evidence for the gene-environment interaction:

  Scarr and McCartney (1983) outlined three types of gene-environment interaction: passive, evocative and active. The interaction is different for each type - eg. in passive interaction parent's genes influence how they treat their children (musically-gifted parents play to their children and encourage love of music). This points to a complex and multi-layered relationship between nature and nurture.