Other considerations aside, DNA analysis is so easy and getting so cheap, its inevitable it will be used in every facet of our lives. So learn to live with it. Or become a luddite hiding in a cave.
Even though you're at the bottom of the comments, I'm inclined to agree. In case you're interested, here's an discussion of how this trend might at least be amenable to creating unique cryptographic IDs without the need for central governance.
As a password, biometrics are notoriously inappropriate (have to use the same one for everything; can't change at will; leave it in the open all over the place). But maybe as a sort of username?
