“You know masseter injections can cause jowls, right?” If only I had a dollar for every time I heard that phrase from fellow beauty editors and friends. Turns out, jowls were the least of my worries.

FaceApp is the hot new app for showing people a smudged, uncanny version of what you’d look like as a baby, an old, or a sparkling thing. The technology works by uploading images of your face to a ...