""Was I in any way wrong to assume that all within that culture would be exposed to those aspects of the culture?""

If there were the slightest vestige of sense in that assumption, one would predict with confidence that there would be some such activity wherever that culture was found. There is no such activity in the south of England, where one third of all British Pakistanis reside. Your assumption is flawed, and needs re-consideration.

""If it caused the behaviour in some, as claimed, I would expect the distribution of effects to be a continuum from actual offending down to zero inclination.
Agree?""

And I would expect that continuum to appear wherever that culture was found
AGREE?

BUT IT DOESN'T!!
AGREE?

""We know that the spectrum is skewed towards non offending as only a minute minority offend.

That is my assumption but social psychology is not my field.
I am open to correction.""

We also know that the spectrum is skewed towards all offenders belonging to a limited gang structure in a very small and tightly grouped part of the country, and to zero offences elsewhere.
AGREE?

You are not apparently open to rational argument, let alone correction.

Don T.