Apparently, the way to argue with a racist is to deliberately conflate two things in order to mislead them.

>in every generation back through time, the number of ancestors you have doubles: two parents, four grandparents, eight great-grandparents and so on. Going back just 1,000 years generates more than a trillion ancestors – 1,099,511,627,776.
>every racist has African, Indian, Chinese, Native American, aboriginal Australian ancestors...there are no purebloods, only mongrels enriched by the blood of multitudes
what is deliberately ignored is that there is a difference between genetic and genealogical ancestors. though you have a trillion genealogical ancestors, you didn't inherit DNA from all of them. in fact you only inherited it from a few thousand of them, which means you probably inherited 0% of your genetic material from those africans, indians etc (unless you have a more recent ancestor of course).

https://www.theguardian.com/books/2020/jan/30/how-to-argue-with-a-racist-adam-rutherford-review
https://www.newstatesman.com/culture/books/2020/02/how-to-argue-with-a-racist-adam-rutherford-review