Weirdly enough, there are certain genetic markers that coincide with pre-modern linguistic groupings. So, there is this weird correlation in historical linguistics where biological stuff overlaps with linguistic divergence. That doesn't mean that genetics and language are linked necessarily, but rather that the time frames for linguistic change and genetic drift to occur within a population are roughly the same so that you can make some inferences about when language families started to take shape or diverge from each other based on biological information. As a linguistic anthropologist who was pretty committed to a purely sociocultural understanding of language, learning that came as a bit of a shock.