I get the concept that given genetic trait A for blond hair, then a relatively small pool of AA or Aa people can spread the trait throughout the world given enough time. I get that.

But isn't it a little more complicated than that? Aren't there other traits that override the blonde trait? If the world consisted of one blond Norwegian and a million dark skinned, dark haired Africans, and assuming the Norwegian got involved in the reproduction routine, and the blond's kids do too, etc, then a thousand generations later would we actually find any blond folks hanging around?