Strength + Counterpoint

A strength of genetic explanations of human behaviour is the supporting evidence from…

Twin studies

For example, McGriffin conducted a twin study on _________ and found concordance rates of 46% for MZ twins and ___% for DZ twins

Depression

20

This suggests depression is at least ______________ since twins who are genetically identical were ___________ as likely to both have the disorder than for non-identical twins

Partly genetic

Over twice

Evidence supporting the role of genes therefore supports the idea that psychological characteristics are…

Determined by our biology

However, since identical twins are usually raised in the same environment, it is impossible to disentangle the role of…

Inherited and environmental influence

For example, if a high concordance rate is obtained, we cannot be sure whether this degree of similarity is due to the fact that they are…

Genetically identical of the cact that they are treated similarly

This heavy use of twin studies to support the role of genes therefore poses ______________ which effect the _______ of research into biological factors

Methodological issues

Validity