You have the right idea. It's important to remember what we'd want if we didn't have any concerns about power abuse. In a perfect world, anyone would be excited that some of the world's best scientists were studying the secrets of their body and would soon be able to offer them opportunities to take control of their health and ageing rather than leaving it to chance. Even better if an enormous sample was pooled for study. This is the only realistic way to move toward a complete understanding of how our bodies work.
There are real potential abuses of privacy, but we shouldn't let those scare us into failing to progress. The fact is, you leave your genetic information everywhere you go. If any restaurant wanted to get into the DNA collection business, they would never run out of material. In the near future, I wouldn't be surprised if some people argued that any genetic material left at their business was their rightful property, and since you made no effort to hide the fact that you were eating off that particular fork, they shouldn't have to avert their eyes from your DNA or deny its association with you. Perhaps on your next visit to any chain restaurant, they could suggest a menu more appropriate to your specific health needs.
I feel you are both missing the point that the kind of abuse we are opening ourselves up to inevitably includes catastrophic abuse as well as everyday injustices. Two examples that spring easily to mind - jury nobbling by organised crime, market manipulation by foreign powers. This is the job of government, legislation, and society, and is not within the remit of private corporations or something that can be left to a theory of market self-regulation. The example that a restaurant left to its own devices could get into collecting data so easily underlines that this needs legislative teeth.
You're right about the potential abuses. However, the only reason we have any kind of biological privacy is because the stuff we leave everywhere is too small for most people to notice. But we are not clean animals. We shed everywhere. I don't think biological privacy in the long term is a realistic goal unless we're willing to make full-body plastic suits fashionable.
More to the point, it's absolutely necessary to research this stuff. The more samples we can get out there, by whatever means necessary, the better. This kind of research will absolutely save lives, and in no small portion.
It's good to keep the security implications in perspective. However, if privacy concerns held back or halted basic research on biology, they would do more damage from voluntary and legislative protections than they are capable of doing by creating advertising profiles.
Counterfeiting money is an example of something which is relatively easy but can be hugely damaging if done on a large scale - we try to make it harder for the casual counterfeiter but mostly we rely on draconian penalties around it precisely for this reason.
There is also an important cultural aspect that makes certain behaviours abhorrent/unacceptable that would need to be tapped into.
Research is a legitimate and beneficial activity that you would therefore expect to be licensed and controlled.
There are real potential abuses of privacy, but we shouldn't let those scare us into failing to progress. The fact is, you leave your genetic information everywhere you go. If any restaurant wanted to get into the DNA collection business, they would never run out of material. In the near future, I wouldn't be surprised if some people argued that any genetic material left at their business was their rightful property, and since you made no effort to hide the fact that you were eating off that particular fork, they shouldn't have to avert their eyes from your DNA or deny its association with you. Perhaps on your next visit to any chain restaurant, they could suggest a menu more appropriate to your specific health needs.