1. Methodology of the Biological approach TWIN STUDIES

2. Biological approach Two types of methodology – Animal experiments – Twin studies

3. Twin Studies What are the two types of twins? How are they formed? Monozygotic Dizygotic

4. Example of a Twin Study Bouchard and McGue (1981) Studied the inheritance of IQ – What is IQ? They compared the IQ scores of different types of twins who were reared together and separately. They were looking for the genetic basis of IQ by using concordance rates

5. Bouchard and McGue (1981) Concordance rate – A score from 0-100% – The higher the concordance, the more similar the two scores are E.g. 100% would be identical scores 0% would be completely unrelated See Pg 13

6. Bouchard and McGue (1981) RELATIONSHIPIQ TEST CORRELATION 86% 72% 60%

7. Bouchard and McGue (1981) What can we conclude from these results about the effect of genes on IQ?

8. Twin studies Why are twin studies used in the biological approach? – Think about the assumptions of the approach With a partner, come up with an answer to this question that is no longer than 3 sentences

9. What do we know now? MZ TWINS are Identical. T or F? What is a concordance rate? What kind of twins have 72% concordance for IQ? Why use twins studies in the biological approach? Key weakness of Twin studies?