RM twin and adoption studies

• Monozygotic 

  • identical twins
  • same eggs
  • Same DNA
  • Same gender, age, environment 
  • May have different friends, class, school
• Dizygotic

  • two eggs
  • Can be same or different gender
  • Non identical
  • 50 of same DNA
  • Same age
• If adopted identical twins will have same DNA different environment 
• Nature

  • genes you are born with
• Concordance rate

  • the measure of similarity the higher the % the more similar (proportion of pairs which share an attribute)
• • one way of finding out whether a disorder has a genetic component is if it runs in families
  • If family members often have similar environments consequently increasing the risk that relatives are exposed to the same environmental risks
  • An alternative approach is to do a twin study. This looks at the concordance rate (degree of similarity) of twins with respect to the disorder being considered. Concordance rates means the probability of one twin having the disorder if the other already has it expressed as a percentage.
• • In a twin study, MZ (identical) and DZ (non-identical) twins are compared. Whilst MZ twins have a greater degree of genetic similarity than DZ twins, it is assumed that both types of twin pair grow up in identical environments. This means the only difference between the twin types is their genetic similarity.
• Adoption study’s mean we are able to see how effects of genetics (nature) effects behaviour versus environment (nurtrue)