Nature v. nurture

• What is the nature v. nurture debate?

  • Seeks to answer the question of whether our behaviour is more influenced by our nature or how we are nurtured
• What is nature?

  • Inherited influences or heredity
  • Descartes argued that all human characteristics are innate and even psychological characteristics are determined by biological factors just like physical characteristics
• What is nurture?

  • The influence of experience and the environment
  • John Locke suggests the mind is a blank slate at birth which is shaped by the environment
  • Prenatal factors include how physical and psychological influences can affect a foetus such as smoking or music
  • Postnatal factors include how children grow up such as their social conditions
• What is the diathesis-stress model?

  • Suggests behaviour is caused by a biological or environmental vulnerability (diathesis) but is only expressed when coupled with a biological or environmental trigger (stressor)
  • e.g. someone who inherits a genetic vulnerability for OCD may not develop the disorder until combined with a psychological trigger like a traumatic experience
• What are epigenetics?

  • Refers to a change in our genetic activity without changing the genes themselves, caused through interaction with the environment
  • Aspects of our lifestyle or events we encounter leave marks on our DNA, explaining why smoking has a lifelong influence even after you quit
  • May influence the genetic codes of our children as well as their children, introducing the life experience of previous generations into the nature-nurture debate
• What is one strength of research into the nature-nurture debate?

  • Adoption studies: useful as they separate the competing influences of nature and nurture - if adopted children are more similar to adoptive parents then nurture is the bigger influence, but if more similar to biological parents then nature is bigger
  • Rhee and Waldman (2002)'s meta-analysis found that genetic influences account for 41% of variances in aggression
  • Shows how research can separate the influences of nature and nurture to see which is most influential
• What is another strength of the nature-nurture debate?

  • Support for epigenetics: in 1944 the Nazis blocked food distribution to Dutch people and 22,000 people died of starvation, called the Dutch Hunger Winter
  • Susser and Lin (1992) reported that the women who were pregnant during the famine went on to have low birth weight babies, who were 2x as likely to develop schizophrenia
  • Supports the view that previous life experiences of past generations can leave epigenetic 'markers' that influence the health of their offspring
• What is another strength of the nature-nurture debate?

  • Real-world application: research suggests OCD is a highly heritable disorder as Nestadt et al. (2010) put the heritability rate of OCD at .76
  • Can inform genetic counselling because it is important to understand that high heritability doesn't mean individuals will inevitably develop the disorder - people can receive advice about the likelihood of developing the disorder if they have a family background in it
  • Shows the debate is practically important to understand the interaction between nature and nurture
• What is one limitation of the nature-nurture debate?

  • Interactionist approach: research suggests the nature-nurture debate is a meaningless distinction as there is a growing body of research highlighting an interaction
  • Maguire et al. (2000) found London taxi drivers had a larger volume of grey matter into their hippocampi as a result of learning so many routes and shortcuts, demonstrating evidence that nurture can affect nature and weakening the value and usefulness of the debate