from the Vice article:
I asked jokes_on_you how they spotted the difference. "I’ve sucked enough toes in my life to recognize when something doesn’t look right," they told me in a Reddit direct message. "Because we can’t dorsi- or plantarflex our 2nd-5th toes independently I knew it wasn’t a matter of the toe being bent. I thought that maybe she has some form of brachydactyly but her Wikifeet page has clear evidence to the contrary. So it was clear to me that it wasn’t her feet."