Well here's the thing. I believe there's definitely something up with the Shroud of Turin. And if I'm correct, then the real Jesus is depicted on that ancient piece of cloth. It doesn't show skin color, but it does show a man who looks more or less like what we see depicted in the art. And a man with shoulder-length hair, a beard and mustache and generally angular features isn't exactly a rarity either in history or the modern era.

In other words, it's quite possible that the real Jesus looked like he did on the shroud, AND Cesare Borgia looked as he was shown in the painting. The artistic license taken by the painter may not have been about their appearance as much as their demeanor. Borgia in that painting has a "deity" look about him. Others liked it and copied it. Today we can scarcely tell the difference, but there may be truth in both.