+15/1000 people in prison have XYY syndrome compared to 1/1000 people in the general population. This shows that the majority is in prison, this can be inferred to support that XYY makes men more aggressive.
+Adler suggests that aggressive behaviour is partly determined by genetics. This supports the existence of XYY theory.
-Jacobs’s study looked at men imprisoned in secure psychiatric hospitals so the data is unrepresentative of the prison population of people with XYY.
-Skinner would argues that XYY syndrome ignores the behaviouristapproach and that nurture has a tremendous role on the way a person carries themselves in life. They could’ve learnt to be aggressive from observing interactions between family members or friends.
-This could cause stereotypes to arise for people with XYY syndrome which would cause them to be treated as aggressive from the get go.
Hirshi concluded that now most people see it as a diathesis stress model, where the environment is seen as a factor that can trigger a person's predisposition to XYY syndrome.