Why do we use twin studies

• Twin studies are used to see if behaviours are shared by those who are genetically similar
• You can see what traits are shared by looking at concordance rates (likelihood that, if one twin has a certain trait, the other twin will have the same)
• The aim for using twins is to investigate the genetic basis of behaviour, if one MZ twin has a particular characteristic and so does the other twin, then the characteristics may be genetic & they share the same genotype – this means there should be 100% concordance rate
• DZ twins who are no more genetically alike than siblings, should show a lower concordance rate. However, most twins share the same environment, so similarities may be due to environmental factors too.