These are all good questions, although some of them remain without an answer. Parkinson's disease, also known as paralysis agitans, is a neurological disorder which is generally seen only in the elderly population but not altogether unheard of in young people. In fact, most of what is known today about the disease has emerged from developments made during the neurochemical era, namely during the latter part of this century. While there is not yet a cure for the disease, there are a number of medications which help slow the progression. Most of my exposure to the disease was at a rehabilitation hospital in West Virginia.
Many people have a lack of facial expressions as if they are without feelings or emotions.
There may be a monotone voice or even a drooling of the mouth. The problem disappears by stopping the medication. Anyone can, of course, but men are usually more prone to be afflicted with Parkinson's disease than women. If you are looking for a link between Parkinson's disease and your genes, forget it. So, you cannot blame your parents or grandparents.