I had the opportunity to tour a greenhouse that hosts over 800 varieties of coffee plants from most of the coffee producing countries. The plants are grown here in Italy for coffee genetic research. Ironically, there are only a few groups working on this type of analysis, so when you consider to the size of the coffee market (2nd largest commodity in the world) it's a big deal.
As consumers, we care more about cup quality the anything else. Environmental considerations, like roasting techniques and brew methods, do play a role in quality, but the real answer lies in the genetics of the bean. About 90% of what you taste is a result of the genetics and only 10% is the rest.
The reason your favorite Arabica variety tastes the same in Guatemala as it does in Ethiopia means that they share the same genotype. Or put another way, a Granny Smith apple tastes the same in the markets in California as it does in the markets of Italy. Why? They are the exact same plant under a microscope. In fact, only a single gene difference will give a totally different size and shape of plant.
So how is this genetic information beneficial to us? We have been using genetics in agriculture and farming since the beginning of time. The animals we farm, like cattle for example, have been bred specifically for their purpose. So when we choose which animals to breed, we are using genetic engineering and the same can be said with crops.
We can breed coffee plants for this very reason - improved quality. But also for defense against diseases, like coffee rust that has been a real concern for plantations in Central and South America. So next time you sip on your favorite Geisha variety from Panama, realize that there is much more to consider then the coffee roaster and brew method you used.
http://youtu.be/r60PBFgr850