Nature-nurture

• The nature-nurture debate – concerned with the extent to which aspects of behaviour are a product of inherited or acquired characteristics
• Heredity – the genetic transmission of both mental and physical characteristics from one generation to another
• Environment – any influence on human behaviour that is non-genetic. This may range from prenatal influences in the womb through to cultural and historical at a societal level. It includes biological influences e.g. the food you eat may affect your mental development and physical growth.
• Interactionist approach – a way to explain the development of behaviour in terms of a range of factors, including both biological and psychological ones. Most importantly such factors done simple add together but combine in a way that can be predicted by each one separately i.e. they interact
• The nature-nurture debate – the interactionist approach

  -Debate seeks to answer --> whether our behaviour is more influenced by nature or nurture.

  not really a debate because any characteristic arises from a combination of both – e.g. eye colour is not completely determined by your genes (eye colour is about .80 heritable Brauer and Chopra 1978.
• Bowlby 1958 claimed that a baby’s attachment type is determined by the warmth and continuity of parental love (an environmental influence). Kagan 1984 proposed that a baby’s innate personality (temperament) also affects the attachment relationship. Therefore, nature (child's temperament), creates nurture (the parents response) so environment and heredity interact.

  Psychologists now want to know what the relative contribution of each influence is.
• Epigenetics = change in our genetic activity w/o changing the genes themselves. Process that happens throughout life + is caused by interaction w environment. Aspects of our lifestyle/events we encounter (smoking/diet/trauma/war) leave ‘marks’ on our DNA, which switch genes on/off. Explains why smoking has lifelong influence even after you stop – changed the way your genes are expressed.

  These epigenetic changes may go on + influence the genetic codes of our children & their children. Epigenetics therefore introduces a 3rd element into nature-nurture debate - previous generations experience
• The diathesis-stress model suggests behaviour is caused by a biological or environmental vulnerability (diathesis) which is only expressed when coupled with a biological or environmental trigger (stressor). E.g. OCD – a person who inherits a genetic vulnerability for OCD may not develop the disorder BUT when combined with a psychological trigger (e.g. a traumatic experience) this may result in disorder appearing.
• Tienari et al 2004, studied a group of Finnish adoptees and found that those most likely to develop SZ had biological relatives with a history of the disorder (the vulnerability) and had relationships with their adoptive families that were defined as dysfunctional (the trigger)
• Nature : innate and genetic influences, usually 0.5 hereditability

  Nature refers to inherited influences, or heredity. Early nativists such as Descartes (1596-1650) argues that all human characteristics (even some aspects of knowledge) are innate – the result of heredity. The general figure for heritability of IQ is around 0.50 (Plomin 1984). Th fact that it is not 1.0 suggests that genetics and the environment are both important factors in IQ
• Nurture: environmental influences (e.g. learning + experience pre- + post natal). Nurture refers to the influence of experience + the environment. Empiricists e.g. Locke (1632-1704) argued that the mind is a blank slate at birth, which is then shaped by the environment/experience. Later became important feature of behaviourist approach.
• Lerner (1986) has identified different levels of the environment.

  •Defined in narrow prenatal terms (e.g. the mothers physical (smoking) and psychological (influences like music) state during pregnancy.

  •Defined more generally through postnatal experiences (e.g. the social conditions the child grows up in)
• Measuring nature and nurture

  The degree to which two people are similar on a particular trait can be represented by a correlation coefficient and is called concordance. Concordance provides an estimate about the extent to which a trait is inherited – called heritability. Heritability is the proportion of differences between individuals in a population in regard to particular trait, that is due to genetic variation. A figure of 0.1 = genes contribute almost nothing to individual differences and 1.0 = genes are the only reason for individual differences. IQ = 0.5
• One strength is understanding the interaction may have real-world implications

  Extreme beliefs in the influence of nature or nurture may have negative implications for how view human behaviour. Nativists suggests 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.
• +ve of research n-n debate is use of adoption studies

  Adoption studies are useful because they separate the competing influences of n + n. If adopted children are found to be more similar to their adoptive parents, suggests the environment is the bigger influence. If adopted children are more similar to their biological parents (no influence on their environment), genetic factors are presumed to dominate. A meta-analysis of adoption studies by Rhee + Waldman (2002) found genetic influences accounted for 41% of the variance in aggression. Shows how research can separate the influences of n+n.
• +Ve is 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 illogical to try to separate nature and nurture influences on a child's behaviour.
• A further strength is evidence for the gene-environment interaction.

  Scarr and McCartney (1983) outlined 3 types of gene-environment interaction: passive, evocative and active. The interaction is different for each type – e.g. in passive interaction parents genes influence how they treat there 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
• Another strength is understanding nature-nurture relates to other debates.

  A strong commitment to either a nature or nurture position corresponds to a belief in hard determinism. The nativists 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.
• -ve is the confounding factor 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 – these 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 a parental divorce having a different meaning to each sibling).
• Even MZ twins reared together do not show perfect concordance rates. Nemeth et al 2010 found 68% of MZ twins shared OCD – suggesting it is a combination of n/n
• Research suggests OCD = highly heritable mental disorder. Nestadt said heritability rate = 0.76. Such understanding informs genetic counselling as it is important to understand that high heritability does not = it is inevitable that the individual will go on to develop the disorder. Meaning people who have a high genetic risk of OCD due to family background can receive advice about likelihood of developing the OCD + how they might prevent it e.g. manage stress. Shows that the debate isn't just theoretical but it's important, at practical level, to understand the interaction between n/n