Kendler et al (2006)

• This study can be used for...

  1. Genes and human behaviour genetic similarities
• Aim


  To investigate the heritability of depression
• Research method

  Correlation (interviews; twin study)
• Participants


  42000 twins from Sweden's twin registry
• Procedure


  The participants were interviewed and assessed for major depressive disorder in accordance with DSM-IV
• Results

  The researchers estimated from the condordance rates in mono- and dizogotic twins that the heritability of depression is roughly 38% - The rate was higher in females. (MZ male - 31%: MZ female - 44%: DZ Males - 11% DZ females - 16%)
• Conclusions

  Depression is somewhat heritable, but environment and stress play at least a big a role (predisposition and stress: diathesis stress theory)
• Evolutionary: Strengths


  - High generalizability

  - Adhered to ethical guidelines
• Evolutionary: Weaknesses


  - No cause & effect relationship

  - Self reported data, unreliable results