I was having a discussion with some friends who have all expressed interest in being genotyped or have been about putting their information into the public domain. They were a pretty savvy lot (half of the six had been genotyped), but one expressed the common sense objection that "someone could find something in the future." In other words, a really creepy stalker could keep running your data through Promethease. Imagine you're a really strange person, and you have a bunch of gentoypes of people who you want to know about, and you design a program which scours the academic literature and constantly notifies you when the individuals in your database pop up with a large effect mutation. I have no idea why someone would do this. Perhaps you could be blackmailed by someone threatening to disclose to your employer than you had a 50% greater chance of a heart attack before the age of 60 than the general population? Whatever the details of the concern, they're general, ranging from inchoate to eloquent. But all this is moot in my opinion. I think in 10 years most people will probably have at least a genotype with the most informative SNPs. I assume that full genome sequencing will be really, really, common. I also doubt there's just going to be one copy of this information. Right now digital security is not that great. People only care when there's a breach. But in reality there are breaches far more often than people realize. Apparently it is common practice for technically savvy organized criminal gangs to exploit security holes at major financial institutions, steal personal data, and then blackmail the institutions by threatening to divulge the information. The institutions usually pay up, as the cost vs. benefit isn't even close. One can imagine similar things occurring routinely when genotype information spreads throughout poorly secured medical databases. All you need is one weak link, and it's out. Right now if your credit card number is exposed because some hackers extracted them out of a leaky database, you call your credit card company and have the card cancelled. If someone gets your sequence you can't have it cancelled. It's out there. It's yours. Forever (barring somatic mutations and ubiquitous gene therapy of some sort). Of course they might get a sequence, but lack a name attached to it. This happens often with other data, which is why firms sometimes make a big show of having no "personally identifiable information" on file. But a genotype by its nature is personally identifiable. If they have a big database they might cross-check and look for matches. If they don't find you, they might find relatives. Even if you are confident you aren't exposed, it is possible a relative of yours is exposed, which would immediately give everyone some information about you in direct relation to your genetic relatedness.