You know, in Russian culture every nationality ("национальность" = ethnic group, not the country where you live) considered to be like Jews. If Jews go to Britain or to America, they remain Jews, as well as when they come to Israel. So are Russians, Uzbeks (ethnically very different from Russians), Kazakhs, Tatars and so on. The confusion comes from the European and (rather) American understanding what is "nationality".

So if definitely Slavic people have lived all their life in Kazakhstan, and even if their grandparents lived there and grandgrandparents came there in the end of 19 c., they, nevertheless, remain Russians, because they are not like Cenrtral Asia mongoloids, and speak Russian, because no one cared to study "ethnic" languages in Soviet times. And Kazakhstan appered as a "state" on the maps only less than 15 years ago. And imagine, when they come to America, they suddenly find out that they are "Kazakhs" now....