Cultural traits are likely to be those that lead to an increased propensity for crime.
Ok let's see, how do I put this? I don't have a life altering alcoholic problem, I don't uncomfortably stare, have an incomprehensible head bobble or go all buck wild with a stick over minor disputes. My "integration" in this society was decent due to a stable home environment, others like me have not been so fortunate.
Perhaps the issue is more to do with the different paths immigrants take and the specific aspects of cultural integrations? I'll add a disclaimer, I don't fully know what would relate to the dishonorable behaviour of certain areas of the UK, you could twist it quite easily to identify poor monitoring of television media influencing childhood behaviour and aspirations as the cause if you really wanted too.
To define as you have would mean every descendent of the African continent who participate in foreign law enforcement have "an increased propensity for crime" too? Or just some.
Edit: I will add that this particular incident seems to have arisen from rallying off the back of a faux hippie political movement, using it as an excuse to blow the valve a little after a bit of global cabin fever.