I kinda want to do it too, but I too am worried about the privacy aspect . Companies now days are pretty much salivating over the idea of selling off every bit of your identity. Supposedly they have to destroy the data at request, but how do you know if they really did it when you ask? Or that they didn't sell it immediately before you asked.
I suppose one thing you CAN do is do it as a group of people like 10+ people, and just put each other's DNA in different vials and keep track. So when the results come in they will be for your partner and not for you. This will poison any database that is used to store your personal info since it will be all wrong. This is probably the key to all this data harvesting now days, to try to poison it with false data.