Sub-Saharan African-derived genetic dirt, mostly from archaic hominids evolving separately from the main human lineage for as long as 2million years (out of the 4million years that separate us from the chimpanzees) has broken through to Europe via Arab immigration. Arabs have an average of 5-10% sub-Saharan genes, which they acquired after the collapse of the Roman Empire as a result of the slave trade. Before conceiving children, it is worth doing DNA tests with your partner to make sure he or she does not have such genes because by some twist of fate, people who have them do not participate in the development of science.