No, Siblings Aren't 'Fooling' Face ID - They're Training It

There have been some fun if silly videos making the rounds over the last couple of days that claim to show twins, triplets, or non-identical siblings "fooling" Face ID into unlocking iPhone X. And, this being iPhone X launch weekend, they're getting a predictably high amount of attention.
Unfortunately, in everyone's rush to be sensational, claim the next controversy, and rack up views, the facts are often being left behind. So, let's back up for a moment, take a breath, put our thinking caps back on, and review just how Face ID works again.
https://www.imore.com/face-id-sibling-fud
-Bill