Well, I have read this entire thread. Trystan, I would like a medal, please

Not much to add to what quite a few people have mentioned before: privacy. Once my DNA leaves my hands I will have no control over where it ends up. And no way of knowing in whose database it will be stored and shared from. Or sold from. Or used in forensics rather than genealogy.
I'm Canadian, but from paper-trail genealogy I know my ancestors are English, Scottish, Welsh and Ulster. With nothing, absolutely nothing else added in. No German great-grandmother, or Swedish or French, nothing. I like to tell my OH that I'm way more British than he is...and he's English

Even if a DNA test says I have, say, a Viking or Asian ancestor, I'm never going to find Sweyn Forklift or Attila the Pun. They are so far back in the mists of time I could never find them, relate to them, or care. For me, a much more interesting way to do family history is to find a documented connection and then apply the times they lived in to them. Put meat on the bones, as someone said. Much more fun.
So...unless one of these tests can prove I've got space-alien DNA in me, I'm not interested. Although, I have to admit, a space-alien connection would be cool. Move over, Mulder and Scully

Cheers,
China