Issues & Debates - Nature-Nurture Flashcards
What are the key features of the nature-nurture debate?
- Nature: innate and genetic influences, usually 0.5 heritability.
- Nurture: environmental influences (e.g. learning and experience prenatal and postnatal).
- The relative importance of nature and nurture.
- Interactionism (e.g. attachment).
- Interactionism in mental illness: the diathesis-stress model.
- Interactionism: epigenetics, the third element.
What is nature?
Early nativists (e.g. Descartes) argued that human characteristics are innate - the result of heredity.
The general figure for heritability of IQ is around 0.50 (Plomin 1984). The fact this is not 1.0 (100%) suggests that genetics and the environment are both important factors in IQ.
What is nurture?
Empiricists (e.g. Locke) argued the mind is a blank slate at birth upon which experience writes - the behaviourist approach.
Lerner (1986) has identified different levels of the environment:
- Defined in narrow prenatal terms (e.g. the mother’s physical and psychological state during pregnancy).
- Defined more generally through postnatal experiences (e.g. the social conditions the child grows up in).
What is the relative importance of nature and nurture?
The nature-nurture debate is impossible to answer because environmental influences in a child’s life begin as soon as it is conceived (perhaps even earlier).
Practically and theoretically it makes little sense to try to separate nurture and nurture (e.g. in twin studies it is difficult to tell whether high concordance rates are more the result of shared genetics or shared upbringing).
What is interactionism?
The focus of the debate is now on the relative contribution of each influence.
For example, the interactionist approach to attachment sees the bond between infant and parent as a “two-way street”:
- The child’s innate temperament influences how the parent behaves towards them.
- The parent’s responses in turn affect the child’s behaviour (Belsky and Rovine 1987).
How is interactionism seen in mental illness?
The diathesis-stress model suggests mental disorder is caused by a biological vulnerability (diathesis) which is only expressed when couples with an environmental trigger (stressor).
For example, Tienari et al. (2004) studied a group of Finnish adoptees and found that those most likely to develop schizophrenia had biological relatives with a history of the disorder (the vulnerability) and had relationships with their adoptive families defined as ‘dysfunctional’ (the trigger).
What is epigenetics?
Epigenetics is a change in genetic activity without changing the genetic code.
Lifestyle and events we encounter (e.g. smoking, diet, pollution, poverty) 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.
What are the strengths of the nature-nurture debate?
- understanding the interaction may have real-world implications
- gene-environment interactions can be explained by constructivism
- there is evidence for the gene-environment interaction
- understanding nature-nurture relates to the other debates
What are the weaknesses of the nature-nurture debate?
- there is a confounding factor of unshared environments
What real-world implications does understanding the nature-nurture interaction have?
Extreme beliefs in the influence of nature or nurture may have negative implications for how we view human behaviour.
Nativists suggest genes determine behaviour and characteristics (‘anatomy is destiny’). This has led to controversy (e.g. 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.
How can gene-environment interactions be explained by constructivism?
People create their own nurture by actively selecting environments 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 illogical to try to separate nature and nurture influences on a child’s behaviour.
What evidence is there for 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 - e.g. in passive interaction parent’s genes influence how they treat their children (musically-gifted parents play to their children and encourage love of music).
Again, this points to a complex and multi-layered relationship between nature and nurture.
How does understanding nature-nurture relate to other debates?
A strong commitment to either a nature or nurture position corresponds to a belief in hard determinism.
The nativist perspective suggests ‘anatomy is destiny’ whilst empiricists argue that interaction with the environment is all.
These equate to biological determinism and environmental determinism, showing how nature-nurture links to other debates.
Why is the confounding factor of unshared environments a limitation?
Research that tried 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 mean siblings may experience life events differently (e.g. age and/or temperament 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.
