Twin studies

• What is a twin study?

  > Used to estabilish nature vs nurture

  > Identical twins share 100% DNA

  > Stay in the same environment
• What are the two types of twins?

  Monozygotic (identical); 100% DNA shared

  Dizygotic (non-identical); 50% DNA shared
• How are twins compared?

  A concordance rate;

  • if MZ twins share behaviour more than DZ twins, the behaviour has a genetic base (nature)
  • if they are about the same or DZ twins share more behaviour, it would prove nurture
• What are the strengths of twin studies?

  > Use pre-existing data, there is no direct manipulation of the twins behaviour - this is ethically sound as vulnerable children are not being experimented on

  > Information is often taken from twin registries which hold information about thousands of twins and numerous variables - Gather information from twins randomly which is more representative and generalisable
• What are the weaknesses of twin studies?

  > MZ twins, same sex and lookalike so they are treated more alike than DZ twins which produces important environmental differences - MZ twins might be socialised the same as each other instead of basing it off genetics, reduces validity

  > Both MZ and DZ twins are almost always raised together in the same environment - Cannot assume that higher concordance rates in MZ twins that DZ twins is due to genetic differences alone