I'm horrified at the vitriol on this thread. This isn't a discussion about why one ethnic group is crap at something - this is a discussion about why there appears to be a tendency for top level sportsmen and women from certain parts of the world to have the edge over top level sportswomen from other parts of the world.
It is quite clear from some of the early responses to the thread that people are perfectly capable of recognising that it isn't a simple equation of skin colour = athletic prowess. There have been mentions of the altitudes of some countries, of the different muscle types produced by certain nations etc. The impact of socio-economic factors has been discussed. People are genuinely interested in the science and research behind this difference, if indeed there is a difference based in phsyiology rather than culture/environment.
There are differences between people from different parts of the world. To deny this would be daft. There are some parts of the world where the people are very small. There are parts of the world which tend to produce tall people. There are parts of the world where it is unusual to see large-breasted women. There are parts of the world which have very distinctive facial features. We are all products of our environment and sport might well be one of the few ways in which the extent of the differences can be evaluated, if someone could come up with a way of factoring out all the other complicating factors.
It is vital to understand differences between different ethnic backgrounds. There are diseases to which certain individuals are more susceptible. There was a recent suggestion that optimum gestation period is different for caucasion and afro-carribean women, meaning that some women should be induced earlier than the current guidelines. Different blood groups can be traced back to different parts of the world - I have one of the rarer UK blood groups and this is almost certainly due to having a recent ancestor from the baltic region.
We are all different and, while we are still a society with enough issues to make it necessary to be alert for casual discrimination and deal with it when it arises, I don't think it is beneficial in the long run for certain differences to be completely taboo as discussion points. By effectively ring-fencing skin colour when you are talking about differences between people, it can seem like you are suggesting that there is something wrong with being different in that respect.
I have never believed that equality comes from pretending we are all the same - I believe that it comes from accepting that we are all different and allowing everyone to achieve the maximum potential of their own unique state.