@exatron
“What the frell does "bred backwards" even mean?”
It’s a form of breeding animals back towards their wild state. The Heck cattle, for example, are a project of attempting to breed the domestic animal commonly known as the ‘cow’ to the extinct, ferocious, slim and tall giant of the plains, the ‘aurochs’ (who were concluded by the Ancient Romans to be completely undomesticable, although obviously someone succeeded at some point in pre-history).
This Nazi might have made a bit more sense if lab rats originally came from a species that was completely black. They don’t, they come from ‘Rattus Norvegicus’ who is basically your average rat, better known as the ‘Brown Rat’ although they are sometimes black, often grey. And in their domestic form, all kinds of permutations and shades of black, white, greys and browns.
Also, white lab rats are white because they are albino. As albinism is a recessive trait you can breed albinos with other albinos for years and years and be certain of not getting any other colour at all.