When my sister and I were kids, my Dad used to take us to short film programs at the state museum and elsewhere. I have a distinct - and apparently very formative - memory of a documentary about a group of people whose feet shared a deformity. Thanks to Google, all I had to do was search for "two-toed people" to bring that image back to life...
These are members of the Vadoma tribe of Zimbabwe, Africa, less formally known as the "Ostrich people." Because it is their custom not to marry outside the tribe, their relatively small gene pool preserves the mutation of ectodactyly, in which the 3 middle digits are absent - the same condition noted in both the hands and the feet of the Lobster Boy.
The Vadoma 1st encountered Westerners in the 1950s by Charles Sutton, who had joined the British South Africa police:
"From the light of a burning fire I could see astonishment written all over the man's face, especially looking at myself, as he later revealed that I was the first white man he had seen, and the first to come to that area. When he gained our confidence as we drank, he beat a drum and several of the tribesmen appeared from nowhere - they just arrived on all sides, men, women and children....During daylight the next morning a number of them came to see who we were. I could see one of them with only two toes on each foot, in a V-shape similar to an ostrich's foot - others had web-like feet."Rusty Theobald, who served in the Rhodesian Air Force between 1966 and 1971, heard about this "ghost tribe" whose ability to disappear when one's back was turned was ascribed to running as fast as ostriches. In fact, the condition slows their walk, but is said to make climbing trees easier. Another veteran of the Rhodesian military reports that the trait - and/or the tribe itself - will vanish, since they have begun marrying outsiders.