The concept of admixture is currently widely being used, both in population genetics research and in DNA ancestry testing discourse. It is assumed to describe the process of gene flow between 2 previously distinct populations that eventually become admixed because of this flow. The concept per se does not require pure or unadmixed populations; the changes are relative and what matters is the level of admixture before and after the event under consideration. However, in this paper, we argue that the concept of admixture as currently used assumes the existence of pure or unadmixed categories. These do not need to have actually existed but to be able to exist in principle. We argue that this is a problematic notion that accrues from the racialist origins of the term admixture, which, as a result, is based on assumptions about purity. We suggest that scientists should be very cautious in their use of this term, especially in science education and communication. We also suggest that the term admixture should be better replaced by terms denoting similarity rather than difference.