gottenham and sheilds

• What do twin studies help us understand about behavior?

  Nature versus nurture
• What types of twins are used in twin studies?

  Monozygotic and dizygotic twins
• How are monozygotic twins formed?

  From a single egg that splits
• How are dizygotic twins formed?

  From two eggs fertilized at the same time
• What percentage of genes do dizygotic twins share?

  50%
• Which traits are purely genetically determined?

  Sex, eye colour, and blood group
• What is the concordance rate for monozygotic twins with identical traits?

  100%
• Can intelligence be purely genetically determined?

  No, it may have a genetic component
• What are the strengths and weaknesses of twin studies?

  Strengths:

  • Assess nature vs. nurture
  • Quantitative concordance rates for comparison

  
  

  Weaknesses:

  • Similar environments for monozygotic twins
  • Difficulty obtaining large samples
• What is a notable weakness of monozygotic twins in studies?

  They share more similar environments
• Why can it be unclear if higher concordance rates in MZ twins are due to genetics?

  Due to similarity in upbringing
• What is a challenge in conducting twin studies?

  Obtaining large samples of twins
• What was the aim of Gottesman and Shields' 1966 study?

  To investigate genetic causes of schizophrenia
• What method did Gottesman and Shields use in their study?

  Data from five studies about twins
• What was the finding regarding concordance rates for schizophrenia in MZ and DZ twins?

  42% in MZ, 17% in DZ twins
• What conclusion can be drawn from Gottesman and Shields' study?

  There is a genetic basis for schizophrenia