People can look at other people at identify who they are...

New DNA tech essentially is giving people the ability to look at a fragment of biological material and identify who they are.

You could say the difference is that in order to recognize someone you need to know who they are. Still, I think the bigger difference is that the DNA ability is new and therefore seems unnatural. However, I still struggle to come up with a major argument why it is that much different.

Do you have a right to be completely anonymous at all times? And in public? My answer would be no.