Nature/nurture

• The nature-nurture debate


  The extent to which aspects of behaviour are a product of inherited or acquired characteristics
• Heredity


  The genetic transmission of mental and physical characteristics from one generation to another
• Environment


  Any influence on human behaviour that is non-genetic. This may range from pre-natal influences in the womb through to cultural and historical influences at a societal level
• The interactionist approach


  The idea that nature and nurture are linked to such an extent that it doesn't make sense to separate the two. Researchers instead study how they interact and influence each other
• What is the heritability coefficient?

  • Used to assess heredity
  • Ranges from 0-1, indicates extent a characteristic has a genetic basis (1=entirely genetically determined)
• What is the heritability coefficient for IQ?

  • 0.5 (Plomin 1994)
  • Means IQ is both genetically and environmentally determined
• What are epigenetics?


  • The change in our genetic activity without changing our genetic code
  • Caused by interaction with our environment which leave epigenetic 'marks' on our DNA
  • These marks tell our bodies which genes to ignore and which to use, it may influence the genetic codes of our children and grand children
• Epigenetics- research support, Dias and Ressler, lab mice

  • Gave male lab mice shocks when they were exposed to the smell of acetophenone (perfume chemical)
  • The mice showed a fear reaction as soon as the scent was presented
  • The rat's children also feared the smell even though they hadn't been exposed to it
  • So did their grandchildren, supporting the idea our environment can influence our genetic activity without changing our code (DNA)
• What is the diathesis-stress model?

  • A model that emphasises the interaction of nature/nurture for most mental disorders
  • The diathesis is a biological/genetic vulnerability
  • This is only expressed when coupled with a biological/environmental trigger (the stressor)
• Research support for diathesis stress model (Tienari et al)

  • Studied Finnish adoptees with a vulnerability to schizophrenia
  • Adoptees had biological relatives with a history of the disorder (the diathesis)
  • Relationship with adoptive families were defined as 'dysfunctional' (the environmental trigger)
• Limitation- implications on nativism and empiricism (AO3)

  • Nativists suggest that anatomy is destiny in which our inherited genetic make-up determines our characteristics and behaviour
  • As a result, this has led to extreme determinism, becoming a scientific justification for linking race, genes and intelligence, leading to eugenic practises that have harmed minority groups through sterilisation
  • Therefore a limitation as has negatively impacted and been used to support racist practises
• Limitation- complications in study (AO3)

  • Hard to determine influences of nature versus nurture
  • Influences of environment is implicated in the fact that twins and siblings that share similar sets of DNA do not experience the same environment
  • As a result, shared and unshared environments suggest the idea that individual differences between closely related individuals is a result of experiencing environmental events differently
  • E.g. age, temperament, divorce, friendships
  • As a result even with MZ twins reared together do not show perfect concordance rates
  • therefore supports view that heredity and environment cannot meaningfully be separated, suggesting within the debate an interactionist approach