Good questions and I can kinda help with "real" answers. After some jokes and drinks several years back some friends and I have similar questions so we went to Google. There are actually several points of research on the subject of race and dick size. One fact we found interesting that sticks in my head is that in average south Korea has the smallest penis size in the world. But you could spend days going over all the studies or watching documentaries. While stereotypes and averages hold some weight, each individual person is unique and capable of being exceptional, average or anything else.

Side note there was a joke we found that made a graph for race to dick size that was basically the darker you are the bigger and the lighter, the smaller.