Genetic explanations

• What do MZ twins share in terms of DNA?

  All the same DNA
• What percentage of DNA do DZ twins share?

  50%
• What do concordance rates measure in twins?

  Percentage of twins sharing the same trait
• What is the concordance rate for MZ twins according to Gottesman and Shield?

  40%
• What is the concordance rate for D2 twins according to Gottesman and Shield?

  9%
• What does Gottesman and Shield's study suggest about genetics?

  Genetics contributes to 32% of traits
• What are the limitations of twin studies?

  • Assumes M2 and D2 twins share similar environments
  • M2 twins may have more shared environment
• What did Tienan et al's adoption study investigate?

  • Two groups of adopted children
  • Mothers with and without schizophrenia (Sz)
• What was found regarding adopted kids whose mothers had schizophrenia?

  They were more likely to have Sz
• What does Tienari et al's study suggest about genetics and environment?

  Genetics has more influence than environment
• What are the limitations of adoption studies?

  • Assumes similarity is due to genetics
  • Ignores shared environment similarities