[mkagenius]

Just the application or would you want to get pinched every time you would want to log in? Sounds really painful.

[tylersmith]

Not to mention changing your DNA if it gets compromised will be difficult.

[Spivak]

I think it's actually could be a pretty good system. It's a piece of information that uniquely identifies you and even if it's totally public it doesn't help someone impersonate you. Sure someone could easily produce a sample of your DNA but they couldn't fake a fresh blood sample taken by the person authorizing you.

[ceejayoz]

Cheek swabs are a thing, and the most common venue for collecting DNA.