Your DNA is 99.9% known anyway, because you’re a human. Only the remaining 0.1% varies between individuals.
I don't care if they run a DNA search on a database that has such broad results that it includes bananas...
Why do I always see this sort of question phrasing on this site in particular?
https://en.wikipedia.org/wiki/Genetic_Information_Nondiscrim...
And if it wasn't illegal then insurance companies would simply just demand DNA before underwriting your policy.