...check out the complete nonsense and pseudoscience in this (triggery, head-hurty, offensive) white supremacist site's "explanations":
http://www.white-history.com/hwr1.htm They claim:
White people are tall and slim with light hair and eyes! Except when they're short and dark with a stocky build and brown hair and eyes! (by that logic, people like the Quechua of Peru would be white?) And then sometimes they're somewhere in between! And the Welsh are totally Mediterranean! (only...Wales is on an island nowhere near the Mediterranean...)
"The only way a gene pool can be changed is if enough members of that gene pool physically mix - physically integrate and have offspring with - a gene pool outside of that original group."
Mmm, no. Gene pools also change by spontaneous mutation. By their logic, those famous finches Darwin studied the Galapagos would still look exactly like the first finches to wander in from elsewhere instead of having adapted so splendidly to the Galapagos environment.
Their argument about "racial superiority" vs. the "environment theory" was completely debunked in Jared Diamond's book Guns, Germs and Steel.
In the rest of the page, they conflate "modern man" with "white man" in a discussion of extinct hominid ancestors, in part denying that white people emerged from a common African ancestor with all other races. Hate to break it to those guys, but all modern humans belong to the same species or there wouldn't be biracial people. One of the definitions of species, scientifically, is that individuals are of the same species if they are able to produce fertile offspring.