Nature/Nurture

• ENVIRONMENT: Everything that is outside our bodies, which includes people, events and the physical world
• HEREDITY: The process by which traits are passed from parents to their offspring, usually referring to genetic inheritance.
• INTERACTIONIST APPROACH: With reference to the nature/nurture debate, the view that the processes of nature and nurture work together rather than in opposition.
• NURTURE: Behaviour is a product of environmental influences
• NATURE: Behaviour is seen to be a product of innate (biological or genetic) factors
• NATURE/NURTURE DEBATE: The argument as to whether a person’s development is mainly due to their genes or to environmental factors
• NATURE: Human traits are innate. The heritability coefficient is used to assess heredity. This is a numerical figure ranging from 0-1 which indicates the extent to which characteristics have genetic basis. A value of 1 means the trait is 100% genetically determined.
• EPIGENETICS: A change in our genetic activity without changing our genetic code: this happens through life and is caused by things in our environment such as lifestyle. Things that we do leave epigenetic ‘marks’ on our DNA. The marks tell our bodies what genes to use or ignore and may affect the genetic codes of our children.
• THE INTERACTIONIST APPROACH: The Nature/Nurture debate is not really a debate about one or the other because behaviour arises from a combination of both. E.g. Bowlby (1958) claimed attachment type is determined by warmth and continuity of parental love, whereas Kagan (1984) proposed that a baby’s innate personality also affects the attachment relationship - environment and heredity interact. For this reason, psychologists are more likely to ask what the relative contribution of each influence is - an interactionist approach.
• 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. a young person who inherits a genetic vulnerability for OCD may not develop the disorder, but combined wit a psychological trigger (e.g. a traumatic experience) may result in the disorder appearing
• GENETIC EXPLANATIONS

  • Family, twin and adoption studies show that the closer two individuals are genetically, the more likely that both of them will develop the same behaviours
  • E.g. the concordance rate for schizophrenia is about 40% for MZ twins, and 7% for DZ twins
  • This closer similarity for individuals with the same genes shows that nature has a major contribution to the disorder
• EVOLUTIONARY EXPLANATIONS

  • Based on the principle that a behaviour/characteristic that promotes survival and reproduction will be naturally selected
  • These behaviours are adaptive, therefore the genes will be passed to subsequent generations
  • Bowlby (1969) - attachment was adaptive because it meant an infant was more likely to be protected and therefore more likely to survive. 
  • In addition, attachment promotes close relationships which would foster successful reproduction
  • Attachment behaviours are naturally selected, only through genetic mechanisms
• BEHAVIOURISM

  • All behaviour can be explained in terms of experience alone (e.g. BF Skinner, classical and operant conditioning)
  • Attachment could be explained by classical conditioning (food is the mother who feeds the baby) or operant conditioning (food reduces the discomfort of hunger and therefore is rewarding)
• OTHER EXPLANATIONS

  • Some explanations are not behaviour or social, but still a nurture perspective
  • Double bind theory for schizophrenia - SZ develops in children who frequently receive contradicting messages from their parents.
  • Such conflicting messages about their feelings prevent the child from developing an internally consistent construction of reality, leading to the symptoms of SZ.
• NATURE/NURTURE CANNOT BE SEPARATED

  • Hebb argued that trying to do this was similar to asking whether the length or the width of a rectangle is more important when finding the area - they both contribute
  • Example: phenylketonuria
  • An inherited disease that prevents amino acid phenylalanine being metabolised, resulting in brain damage
  • If detected at birth, an infant can be given a diet droid of phenylalanine and thus avoid brain damage
  • If prevented through environmental manipulation, is this condition nature or nurture?
• NATURE AFFECTS NURTURE

  • Plomin et al (1977) “reactive gene - environment interaction” because the child is reacting to genetically influenced behaviour
  • Identified a second kind of interaction - passive influence e.g. a parent with a genetically determined mental illness creates an unsettled home environment. In this case, a child’s mental disorder could be due to indirect, passive effects
  • Third interaction “active influence” (also known as niche picking) as children grow older, they seek out experiences and environments that suit their genes
• DNA METHYLATION

  • DNA methylation works by adding a chemical group to DNA. Typically, this group is added to specific places on the DNA, where it blocks the proteins that attach to DNA to read the gene. This chemical group can be removed through a process called demethylation. Typically, methylation turns genes 'off’ and demethylation turns genes ‘on’
• HISTONE MODIFICATION

  • DNA wraps around proteins called histones. When histones are tightly packed together, proteins that ‘read’ the gene cannot access the DNA as easily, so the gene is turned ‘off’. When histones are loosely packed, more DNA is exposed or not wrapped around a histone and can be accessed by proteins that ‘read’ the gene, so the gene is turned ‘on’. Chemical groups can be added or removed from histones to make the histones more tightly or loosely packed, turning genes ‘on’ and ‘off’
• NON-CODING RNA

  • Your DNA is used as instructions for making coding and non-coding RNA. Coding RNA is used to make proteins. Non-coding RNA helps control gene expression by attaching to coding RNA, along with certain proteins, to break down the coding RNA so that it cannot be used to make proteins. Non-coding RNA may also recruit proteins to modify histones to turn genes “on” or “off.”
• REAL WORLD APPLICATION

  • OCD, according to Gerald Nestadt et al (2010) has a heritability rate of .76. 
  • This can influence genetic counsellors, who can discuss how best to prevent OCD developing with those that are vulnerable to develop it
  • The association between nature and nurture here means that there is practical benefit for the patients, not only from diagnosis onwards, but before that.