Jonah is gross and he totally skeeves me out. Talk about having too much of a good thing.
As for the whole "myth," trust and believe, I've been surprised and/or disappointed by men in that department, no matter what color they are. And I'm saying this as a black man. There are big black ones, but I've seen black guys with little ones, just as I hooked up with a nerdy white dude who was very well endowed. You just never know and can never strictly judge based on race.
Hands and feet do not necessarily correlate with penis size since the human penis is an appendage that is independent from bone growth or size. I think most (but not all) other species do have a penile bone.
I've noticed that build and weight are usually better indicators. In my experience, lean men with smaller asses, slim waists, and skinner legs tend to be the most "blessed" in that department, but that is more of a perception/contrast issue. Height can be a factor too - there is a reason why there are so few tall male porn stars in the industry.
However, there are always going to be exceptions and outliers.