More than 7,000 languages are spoken in the world. This linguistic diversity is passed on from one generation to the next, similarly to biological traits. But have language and genes evolved in parallel over the past few thousand years, as Charles Darwin originally thought?
For the fascists just yet another description of reality that they need to ignore and ad hoc and distract people from, in order to push their idiotic prescriptions. It's like they're trying to cover the Sun with a sieve, one more hole won't do much of a difference.
Although this hole is specially relevant when we take cases where people shifted to IE languages (see: plenty Jewish varieties, colonial languages) or from IE languages to something else (see: Hungarian, Maltese) - both throw a rotten egg at any claim of intrinsic relation between culture and race, or that some cultures would be intrinsically superior.