There is widespread, inveterate deprivation and socio-cultural corruption amongst teenagers in both the north and inner-city London. Ethnicity is indeed irrelevant here, as one inherits their behavioural traits from the presence of surrounding salient behavioural traits; i.e., they only act like that because they are surrounded by other people who act like that, which is why there is spatial confinement of particular cultures and socioeconomic conditions.
Increased emphasis is placed on ethnic minority groups because they are physically distinguishable from the majority population. When discussing problems in Glasgow and other areas with high rates of gang crime/social problems amongst ethnically British teenagers, nobody says it's a 'white problem', and correctly point out their upbringing and surrounding conditions are the cause that must be addressed. However, when this problem is replicated in inner-city London, all of a sudden their ethnicity becomes relevant and it is a 'black problem'. The lack of consistency is problematic and highly misleading in the process of addressing and subsequently rectifying the actual problem of socio-cultural, economic and environmental deprivation.