According to Relationship between vertical jump and maximal power output of legs and arms: Effects of ethnicity and sport Scandinavian Journal of Medicine & Science in Sports Volume 25, April 2015, Pages e197–e207 :
The hypothesis that ethnicity and sport practice influence the relationship between maximal power in cycling (Pmax) and countermovement jump (CMJ) has been studied by relating CMJ and Pmax in two groups (volleyball players, VB, and physical education students, PES) including subjects with Caucasian (67 C) or West African (39 WA) origins.
Within WA, CMJ was significantly higher in VB (0.732 ± 0.057 m) than in PES (0.661 ± 0.082 m), although there was no difference in Pmax (14.7 ± 1.7 vs 14.7 ± 1.9 W/kg). CMJ was significantly higher in WA (0.69 ± 0.08 vs 0.65 ± 0.09 m in C, P = 0.002) .
In other words, the study is saying that West Africans jump, on average, 4 centimeters higher than Caucasians, and that this is a significant result.
Influence of ethnic origin on predictive parameters of performance in sprint running in prepubertal boys. International Journal of Sports Medicine 2005 Nov;26(9):798-802 finds that Afro-Caribbean boys jump vertically 36.77cm versus only 31.12 cm for Caucasians.
See also Leg muscle power in 12-year-old black and white Tunisian football players Research in Sports Medicine 2011 Apr; 19(2):103-17 :
A total of 113 children (white group (WG) = n = 56; black group (BG) = n = 57) participated in this investigation. ...jump and sprint performances of the BG were significantly higher than the WG
See also Racial/ethnic variation in the motor development and performance of American children Canadian Journal of Sports Sciences 1988 Jun;13(2):136-43:
Black children of school age, particularly boys, perform consistently better than White and Mexican-American children in running speed (dashes) and the vertical jump
African Americans in Sports: Contemporary Themes cites to the above reference and states:
In general the literature suggests that African American children, particularly males, perform better on average in sprinting and jumping tasked (vertical and broad jump) than do Caucasian children