Nature Vs nurture


Introduction and genetic influence

  • Genetic influences include genes, evolution and abnormailities wheereas environmental influences inlude culture, society and parents. Both contribute affect how human behave however the debate is the balance between the 2, e.g. does genetics have mroe of an influence on bahviour or is it the environment?
  • Genes - things that are inherites from parents that decide how tall we are, hair colour and how we think. Many studies show genes play a big part in influencing behaviour.E.g. Horn et al (1979) testsed members fo texan families whi had adopted children shortly after birth. first correltaion between IQ were positive between children and adopted parents, however 10 years later positive correlation between children and biological mothers.
  • Shows intelligence inherited by parents meaning genes determine how clever a child can potentially be. However, environment thye are in that results in whether they reach their potential. E.g. child has genes to be intelligent but have unsupportive parents and dont do homework, results in grades being low. Have capability to do behaviour but choosing not to.
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Genetic influence (continued)

  • Mental illness. Joseph (2004) concordance rate between MZ twins for shcizophrenia is 40.4% and in DZ twins it is 7.4%. McGuffin et al (1996) found depression concordance rate for MZ twins were 46% and DZ twins 20%.
  • Both studies show genetics play a part in condordance rates with different mental illness. However, MZ share all of their DNA so if genetics were just to blame, we would expect to see a concordance rate of 100%. Because its not, indictaes environment plays a part in the development of certian mantal illnesses - Links to diathesis stress model - underlying bioloigcal cause but needs and environmental factor (SLE) for the symptoms of the illness to show.
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Environmental influences

  • Main environmental influences is in the form of aggression. Shown by Bandura (1961) - if children saw an adult behave aggresisvley, likely to repeat behvaiour. Bandura said observer must pay attention to the model, be bale to produce the action and be motivated to do so. Shows agression is learnt.
  • However, aggression may have genetic cause. Retz et al (2004) - association etween the 5-HTTLPR gene and violent behaviour. Shows genes can explain why some people are mroe aggresisve than others. 
  • Reactive influence - genetic bahviour can lead to an environmental change which effects developement. E.g. gene for aggression leads to aggressive repsonse. This cause an aggressive environment meaning aggressive repsonse will continue to show.
  • Brain adaptaion. Maguire et al (2000) - taxi drivers showed that region of the brain associated with spatial memory was bigger conpared to controls - indicates hippocampi responded to increase in size so cound remember more street names and routes.
  • Pascal-Leone et al (1995) - region of the brian that controls finger movement bigger in piano players. Both studies show that the brain adapted to the type of person the individual is. However, brain adapting is not all caused by environment. Needs to have the predisposition to be able to change - brain have ability to change from birth (genetic) and changes accoridng to the individual.
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