P: There is research support for the genetic explanation from family studies

E: Research has found that if one person in a family has OCD, relatives are more likely to have it too

E: This supports the explanation by suggesting that OCD is partially inherited.

P: There is further research support from twin studies

E: Twin studies have shown that 68% of identical twins share OCD

E: This strongly supports the genetic explanation by suggesting that there is a genetic basis for OCD, as identical twins share 100% of their genes

P: No twin study has found a 100% concordance rate in identical twins,

E: This means that biological factors aren't the only factor contributing to OCD. For instance, environmental factors may also play a role. Twins studies supporting the explanation may be better explained by environmental factors as twins share the same environment and are treated more similarly

E: This is a weakness as the high concordance rate from twin studies may be influenced by their environment and the genetic explanation doesn't consider this

P: Argues that OCD is a complex disorder and it is highly unlikely that only a few genes are solely responsible for its development.

E: For instance, the diathesis-stress model argues that genes produce a vulnerability to OCD, but environmental stressors determine whether OCD develops.

E: This suggests that biological and environmental factors combined influence whether a person develops OCD, which seems a more likely explanation