There are family names that describe physical features. So one could assume, that in the very distant past, when family names became common in Europe (and maybe other parts of the world) an ancestor of, let’s say, Mike Long, was actually 6 ft 4 in tall which led his peers to call him “Long”. One could further speculate, that, to some degree, this physical feature was inherited by his descendants through the centuries up to the present day Mister Long.
Now obviously, nowadays, these family names which were created dozens of generations ago usually don’t have any meaning.
But I wonder: If one would measure the height of all persons who bear the family name “Long” and all bearers of the family name “Short” and compare the results to the general population, is there any chance that the Longs are actually on average taller and the Shorts are actually on average smaller than the general population than could statistically be expected?
To broaden the data base of this study, one might include family names from other languages, like Klein oder Petit which mean short in German and French.
The problem is that there are hundreds of millions of people who are descendants of the original Short and Long. Most of them aren’t called Short or Long, but all of them descend from both Short and Long.
There’s a tributary of the Anacostia River called the Long Branch, but it’s so short that it doesn’t even make an appearance on this map. Thus we have a situation where the negation of the OP’s hypothesis holds, in that the Long Branch is actually on the shorter end of the distribution of Anacostia River tributary lengths.