FWIW,
I once worked for a man that had severe birth defects that caused him to have abnormal hands. 3-4 'fingers' per hand. Although the digits were used as fingers, they did not really 'look' like fingers. Very sad defect since his son was even further disabled.
There is a congenital birth defect that does cause a person to have few if any fingers on their hand.
Norman, my employer, was able to overcome his birth defect and was a heck of a nice guy. His son, with abbreviated arms and few (maybe 1-2) 'fingers' was able to live a productive life.
I do not know xFatboyx, but I do know of the existence of a this type of birth defect.
Norman could fire any handgun, his son, I think, used shotguns and rifles.
TRG
ps. DrJeffAllen, and Kidlightning might be able to add more details.