Feel free....I've trained in gyms primarily in South Texas and this is what I see in practically all of them. I'd be interested to see if anything I've said holds any water.
Without being Stereotypical ( which might be impossible, if not hard ) they are as follow from my personal experience ... and mind you, because I'm both Black and White I'll try not to pick sides or favor one over the other

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Let's start with Asians : They are all, in my Gym, typically Short. They have great Calves and Legs in general, however, tend to lack Upper Bodies as well as overall conditioning.
Latinos/Mexicans ( who knows ? ) : I have yet to see one in GREAT condition ... I've seen quite a few in subpar condition though. From my experience they have pretty good Upper Bodies but VERY SMALL Lower Bodies. Quite a few I know have short Arms as well ... not that that matters.
Whites : Because the White race is so diverse it's hard to focus in on this particular Group, however, I know LOTS of White guys that are big and COCK STRONG ! I mean strong as a fucking OX ! I think that for the most part, Whites have great overall builds although they tend ( NOT ALL ) to be a little thick in the Waist. If a White guy is really conditioned at my Gym, then he tends to be not very big at all and vice-versa.
Blacks : There are not a lot of Black guys that work out at my Gym compared to the other races, however, those that do workout look GREAT ! You are right, in a way, because not a lot of them have GREAT lower Bodies, however, I hardly ever see any of them TRAIN LEGS ! They're all rippped for the most part except the really obese ones ... Tiny Waists and Joints. And, YES, HORRIBLE CALVES ! The great thing about being Mixed ( Interesting enough, German on both sides of my Family ) is that because my Father is White I have lower inserted Calves ... and that CERTAINLY makes a difference when competing. There's my 2 cents.