>>536648
>>536674
with the exception of Y-DNA on the paternal lineage (on Y-chromosome so males only, determines about 1% of a male's DNA) and mtDNA on the maternal lineage (only females pass on, but it's a tiny piece of DNA that doesn't determine much, more of a marker), we only have DNA from the most recent 16 generations
an endless stream of white DNA would eventually wash out all of the non-white admixture, but it would take 16 generations in total. the inverse is also true, where many generations of non-white DNA would eventually replace all of the white genes, but granted that a halfie is already too brown, we don't care about that as much.
in theory, if you were to DNA test a whole population, weed out foreign Y-DNA (even if they're essentially white, just send them to colonize foreign lands), promote high birthrates from the 100% population, you could eventually wash away any 1/4th, 1/8th, 1/16th mutts, because once it gets to 1/32768 (if math correct), there would be nothing left
but that would take so long, it would be more practical to go into records or DNA test and find every individual that isn't pure and send them to colonize foreign lands
basically it's slightly reassuring that if there's like 1 foreign absorbed per 1,000, as long as their Y-DNA is European or if they are female, there would eventually be no permanent impact on the genes. it wouldn't be like 99.99999% white forever, in other words (unless you count mt-DNA, which isn't that significant and can be tested for like Y-DNA)