Nargis ,
The Pentagon wants You !
Bio_Chemistry Grad :
....with a Flair for the working of the Brain 
i am no expert, but i think if you look at the people and who their leaders are you may find the answer to that.
i believe it completely depends on the environment of the individual on how they react to certain situations. and sometimes, maybe a small population who are educated enough to act differently.
if you grow up in a country where the punishment for a crime is stoning or chopping off a body part, then if a crime is committed against your most treasured possession such as religion, would expect anything less than a violent reaction?
it is how they are trained, taught and the environment around them.
if we consistently watch certain sexual acts - they would then become the norm and no longer be taboo - correct? because that would be what we are exposed to and used to.
same idea.
no one needs to study that.