Kaij twin study of alcohol abuse

• Aim

  to see whether alcoholism can be explained in terms of hereditary factors
• Method

  looked at 310 male Swedish twins

  at least one twin had experienced problems with alcohol abuse

  interviewed the twins to collect information about drinking habits and whether they were identical or non identical

  48 identical

  126 non identical
• Results

  among the sets of twins who has both experienced alcohol abuse

  61% were identical

  39% were non identical
• Conclusion

  alcoholism is a result of hereditary factors as there are more identical twins with alcohol problems than non identical twins as they share 100% genes
• strength

  supported by later research

  Kenneth Kendler conducted a better controlled study using a larger sample and found that if one twin was alcoholic their twin was more likely to be alcoholic if identical than non identical
• weakness

  -lacks validity

  the data on identical v non identical twins was collected by self report from one of the twins or a family member

  -doesn't explain all causes of addiction

  not all identical twins were both alcoholics so genes can't be the only answer for addiction