Mixing Genes

It seems that some people think that the ressessive gene that produces the man who is lacking in melinen is stronger than the dominant melinen producing gene that produces color. Therefore, when the non melinated American who came from somewhere else mixed with the melinated African, it wiped out both Africa and Europe. Is there something wrong with this picture? I may be wrong but I don't think genetics works this way. If the afore mention premise were fact, then the New man would be as much one as the other. It seems to me that color is not the real issue. So What is the real issue. It seems to me there is no difference in one man changing the rules to fit his agenda than the other? What do you think?