Genetic

• Genetic explanation

  Genes for schizophrenia can be passed from parents to children
• Rosenthal: the Genain Quadruplets

  All 4 children ended up developing schizophrenia, 3 of which were hospitalised at least once, suggesting that there is a genetic component - there was a history of mental illness in the family

  
  

  However, they grew up in an unstable environment so there may have been an environmental element
• 2 ways of studying the roles of genes

  Twin studies and adoption studies
• Twin studies

  Look for concordance - the number of second twins who have a characteristic given the first twin has it
• Problems with twin studies

  - results in small samples as it's hard to find twins who are both willing to take part

  - the usually grow up in the same environment so characteristics may be due to nurture rather than nature
• Adoption studies

  When someone has a certain characteristic, their biological and adoptive parents are looked at to see if they have the characteristic

  - determines whether it is due to nature or nurture
• Problems with adoption studies

  - they may have spent significant time with the biological family before adoption

  - adoption can be traumatic so not a representative sample
• Gottesman & Shields: aim

  To review research on genetic transmission of schizophrenia
• Gottesman & Shields: method

  Reviewed 3 adoption studies and 5 twin studies - one of the twin studies was their own
• Gottesman & Shields: participants

  - 711 people with SZ in adoption studies

  - 210 monozygotic and 318 dizygotic twins
• Gottesman & Shields: findings

  More children with biological parents with SZ developed the disorder

  Monozygotic twins had a higher concordance rate than dizygotic twins
• Polygenic explanation

  Schizophrenia is determined by multiple different genes
• O'Donovan et al

  Found that genes which are active in the immune system seem to be linked with schizophrenia
• Strengths of the genetic explanation

  - supporting research finding high concordance in twin studies
• Weaknesses of the genetic explanation

  - there is never 100% concordance so other factors must be involved

  - methodological problems with research - twin studies are correlational so cannot determine cause and effect