Okay, so reading the wiki on this. Heh.
Rudolph von Goldenbaum's ascension is basically that of Hitler. It seems Rudolph was a white supremacist to the extent that he only allowed people of Germanic descent to attain nobility status and rule. When we look at his
Inferior Genes Exclusion Act, however, it is described as follows: "At its heart, the IGE Act was a policy of forced sterilization directed at people deemed to be abnormal or inferior. This included the poor and the handicapped. People considered to be mentally ill were summarily executed." There is no mention, as far as I can see of non-whites being targeted for mass-murder.
We can reasonably assume that the Empire had its roots in
our Earth, with its usual racial make-up. Considering that by the time its precursor, the democratic
Galactic Federation, was established 8 centuries from now (year 2801), the vast majority of humans in the system would be non-white, all pretty much mingling on equal terms. To be honest, by that logic, it'd be surprising that Rudolph would be a pure caucasian, or that he would conceive of politics along racial lines (for racial lines to be political, they have to correspond - or at least
seem to correspond - in a significant way with socio-economic status, because otherwise you can't mobilise people along such lines, and thus race becomes useless as a political tool). This would be highly unlikely in a galaxy full of mixed people.
Furthermore, even if non-whites were targeted by the IGE, the genocide killed off only 1.3% of the population. This still means the vast majority of the Galactic Empire should still be non-white. (The low number alone suggests non-whites were not a target, because no way did they only make up 1.3%). In fact, it'd be surprising to find enough people who could claim direct descent from Germanic roots by the time of the Galactic Empire in order to rule 25 billion people, that even Rudolph's own policy does not make sense.
So anyway, even if Rudolph (somewhat startlingly) grew up a racist, he didn't kill off all or even most of the non-whites. He merely stopped them from gaining top positions. You could assume that many of them would have lived as serfs and thus a massive portion (easily the majority) of people that escaped with
Arle Heinessen in the Great Exodus should have been non-white.
So these things combined, I am now surprised at the lack of ethnic 'majorities' on
both sides, not just the FPA. Perhaps I previously did not question this lack on the side of the Galactic Empire because I always knew it was modelled on Prussia (certainly, I'm not surprised that the powerful people in the GE are all white). But given the historical evidence, it really doesn't make sense, and I'll just put the racial make-up down to Tanaka's own biases.