Many Mexicans have a high percentage of "Native American" admixture in the gene pool. The result: IMHO, lower-end Mexican "culture" is very drunken, and extremely violent.
I can understand why this might be considered a "racist" statement. But if law enforcement personnel is made as aware of it as they are of the extreme alcohol and substance abuse problems around Indian Reservations, it might be useful.
Political correctness will be our downfall.
Some recent studies have concluded that various cultures that used alchohol for centuries had no problem, but where it was introduced to new groups of people they did not do well with it for a long time, some have not adapted to it yet, perhaps because of some enzyme as you noted. Kind of a biological evolution to metabolize booze, I suppose.
I found this earlier doing some research. In the early 1900s a Native American caught in Indian Territory with booze got 4 months jail and a $100 fine. US District court. If you were an Indian, you couldn't even drink at home!
Another post talked about an illegal alien that didn't go to jail after 14 dui arrests, but if you were an Indian in the USA not long ago you sure did. Shows how far we've come, baby! lol