Such poisoning could have been another cause for the development of the werewolf myth. One final possibility lies in the diseases Rabies and Porphyria. Rabies, however, only lasts for a short while once the symptoms have developed, and then the victim dies. Rabies might have caused victims to briefly take on the appearance of a mad beast, but they would not lived to attack beyond this short timeframe. Porphyria, if untreated, leads to extreme sensitivity to light and degredation of the skin, thus producing a victim who rarely ventures out before nightfall and whose physical appearance is sinister.
Mental disturbances accompany the physical symptoms.
This disease is also genetic and therefore could have given rise to the notion of cursed families, as it often does not manifest until an age whereby the victim would have reproduced. There have been a few celebrated cases of feral children, such as inspired Mowgli in The Jungle Book. Many cases have been reported over the centuries but there is little documentary evidence for most of them. These children seen to have retained a propensity to run on all fours rather than walk upright, to eat raw meat rather than cooked meals, and have extreme problems learning any human language. It is difficult to say whether the children already had a mental disorder, whether one was induced by their upbringing, or anything else about them.