There have been studies showing that individuals from two different races, for example Caucasian and West African, are usually more similar genetically to some members of the other race than to some of his own. What is meant by this? How is it possible considering that people of the same race share much more recent ancestry than people of different races? Then later you see graphs showing genetic clusters, how can there be clusters if people aren't more similar to one another for being of the same race? Did they use mixed race individuals for these studies? Are the parts of the genome that make two people look more similar to each other random parts or specific ones, what do these parts do? And finally in the global similarity section of 23andme, one can see the groups he's most related to, how is this possible?