[alistairSH]

And not even a unique user name. Twins and other relatives can pass for each other.

[JohnFen]

And with facial recognition, two people don't even have to be related. I knew a guy who looked so much like me that he grew a mustache purely so that our own friends could tell us apart (which is how I know I look terrible with a mustache). There's zero chance that facial recognition could distinguish us.

He and I weren't even remotely related.

[spullara]

there was also zero chance a TSA agent could distinguish between you either though

[wnoise]

Which means a second factor is needed -- and we already have IDs.