They can use it to build their own databases or flesh out the ones they have. They might possibly sell it to research firms for their use. Lots o reasons they are NOT getting my DNA. Call it conspiracy theories if you want, but they probably have a lot of reasons and not all of them are going to be something that's good for you.
Thanks for the links, Chasing Hawk. Those are very enlightening.
Here's one concerning DNA mistakes by police that's a bit scary.
http://dnapolicyinitiative.org/polic...ror-and-fraud/