For example, the reason why there are more black people (or african americans) in US jails is not because they are more criminal, but because they are verifiable get harsher sentences for the same actions as US Americans from other ethnicities.

Isn't this the old "nature vs nurture" argument from psychology?

It could be possible that there are both genetic and cultural reasons.

One study shows Large Differences in Testosterone Excretion in Korean and Swedish Men ..., this is only one of many studies which shows a different bio-chemical makeup between races.

Bio-chemical differences between populations can definitely account for differences in behavior across large groups.

I don't think that makes any race or other group "bad" or "negative". What is a disadvantage in one situation can also be an advantage in another situation.

Also I recognize each individual is different so people can definitely exist outside the norm for any group.

It seems in your case you have come to the conclusion that nurture is 100% the cause of any behavior and nature is 0%.

I don't find your argument convincing because you only said it is true. You never said why it is true.