Since humanity appeared in Africa, in countries such as Kenya, Ethiopia, Uganda or Tanzania, such thing as "pure white european blood" can't exist. Every human on this fucking planet has an african ancestor.
Bingo. And what is sad is that there are some who are completely blind to this fact.
Let us take Russia, for example. Russia is a pretty big damn area. One with 160 different ethnic groups within. Many of those groups can be traced to Asia, the Middle East and, yes, Africa.
How about the Germans? Well, a lot of Germans come from the Vikings (as do a lot of Europeans), coming directly for many Scandinavian countries. Of course, it is not that simple - many come from different ethnic groups from the British Isles, and quite a few came from the Greater Roman Empire, of which quite a few came from...wait for it...wait for it...wait for it...North Africa. You might THINK you have your family tree all figured out, but the crazy thing about family tree is that there is no start, there is no singularity - the deeper you dig back, the more that you find that there is a lot more digging to be done (I had a rather serious genealogy kick about seven years ago, so I quite understand the complexities of tracing one's roots).
This whole ethnic mixing thing has been going on for quite some time - for literally hundreds of thousands of years. We are human beings, and we like to fuck each other. The color of one's skin does not diminish those wants for normal people, and many times is heightened by what we deem "exotic". It is only those who willfully narrow their own minds who see the color of skin as a divider.
Hell, I look at my own family tree. Like most in the U.S., I do have quite a bit of Irish and German in my blood, but we also have touches of Welsh, Native American, French, Italian, Spaniard and even African (one of our distant relatives is George Washington Carver, a discovery which thrilled me).