Not to be all black helicopter like, but one real consideration for this kind of data may be in end of life care. One of the keys to socialized medicine revolves around the fact that the last 14 days of someone's life is often the most expensive and highest burden on the medical system. Does it make sense to keep people alive when you know they will die anyway and could this kind of information also be used to discriminate against people in a socialized system.
I do not want to open up the emotional argument on obamacare again, I am just saying that the greater good argument also has the potential to create these kinds of social dilemmas and there needs to be checks and balances in place to prevent. History would tell us we cannot trust politicians on either side of the aisle to look out for our best interests.
Likewise, however I am sure the insurance companies would love to have this kind of data to charge you higher premiums based on your risk pool or exclude you from insurance entirely. It creates a bit of a no win situation unless the data is kept private in both cases.
Lets just hope a Hitler type doesn't get into power again I guess.
My real concern is how this could impact the lives of my children, and how much of this information on me can be applied to my offspring. Of course if it got that bad the government would probably just pass a law mandating testing for newborns similar to vaccines and such. Actually who is to say that aren't all ready doing some of this in California with the genetic newborn screening they all ready do.