Penis length and its correlation to Ethnicity
Penis length has alot to do with the suspensory ligament that attaches the penis to the pelvic bone.
The Genetic / Ethnic Factor
Among the different ethnic groups and their respective genetic origins there are concrete differences in penis size, particularly in what concerns the anchorage of the suspensory ligament.
Therefore, the suspensory ligament anchorage is located at the back in Negro men and their penises are completely outside of the body, this determines a very large penis that is slightly elevated during the erection.
For Caucasians, the suspensory ligament anchorage is located forward, what determines a somewhat shorter penis with an erection that is practically perpendicular to the body.
East Asians have a very forward suspensory ligament anchorage, which means that a relevant part of the penis is hidden inside the body; when erect the penis is almost parallel to the body and, in many cases, this results in an upward curvature.
Individuals of mixed race are closer to one or the other description, depending on their predominant genetic features.