I don't really see this working too well in South Asia either.  
 
The Pashtuns aren't exactly seen as the harbingers of civilization in modern day Pakistan, for instance.

So, if the b-w IQ gap were due to differences in socialization, the gap between blacks and whites would be largest among children and smallest among adults.  
What you have described is the opposite of the pattern you would expect to see if the differences were due to socialization.