I'm pretty sure I was involved in that discussion, but shall endeavour to read it.
Yes, a google of the crime statistics does show that ethnic minorities commit more crimes. However, these are crimes that have actually been accounted for.
Take this situation. A police force can concentrate on a limited number of people, I'm sure we agree on this as the force is a finite size. The police assign 2/3 of their officers to the area of ethnic minorities, and 1/3 to an area with fewer ethnic minorities. Shock horror, 2/3 of the crimes that people are arrested for a committed by ethnic minorities, and 1/3 are committed by the others.
Now, I'm not saying this is actually the case, but this is very much a plausible scenario. When I read that sort of statistic, I make the assumption that not everyone has been policed equally, and not everyone has been caught for their crimes.
Can you see, then, why I doubt such statistics?
Perhaps ethnic minorities do commit more crimes, but statistics like those are not sufficient evidence, in my opinion.
With regards to your other point, I don't think our cultures are as different as you seem to suggest. All cultures are very similar to some extent. I can understand your point, but you would do well do define it like that when you start arguing about it.