Holy crap, some people
R sailing very close to the wind.
Dude, skin colour or "race" would have very little to do with the basis of your arguement. Last time I looked USA and Ingerlund weren't "black" nations. If there are modern doping programs in a country such as the USA then you should expect sporting teams to have representitives of every colour and "race" in a similar percentage as they are represented in the country as a whole.
As for black athletes performing better in some sports such as running and jumping, there is scientific evidence to support this in regards to having longer fast twitch muscles (or something along these lines, it's been a long time since I read the article). Similarly, whites shorter muscles are supposed to benifit them in some strength sports such as power lifting, but I would hazard to guess thier general higher socio-economic status allows them access to better quality PED's, so that's advantage enough.