<a href=https://explorable.com/cause-and-effect>Establishing Cause and Effect</a>. Cause and effect is one of the most commonly misunderstood concepts in science and is often misused by lawyers, the media, politicians and even scientists themselves, in an attempt to add legitimacy to research.
You can't catch cancer from anyone, in any way. Cancer is not contagious. You can't catch HIV/AIDS just by touching somebody. The AIDS virus is not found in sweat. Yes, you can catch a cold, or the flu by shaking hands with someone if you then put your hands on/near a mucous membrane (eyes, nose, mouth).
Essential tremor vs. Parkinson's disease. Many people associate tremors with Parkinson's disease, but the two conditions differ in key ways: Timing of tremors. Essential tremor of the hands usually occurs when you use your hands. Tremors from Parkinson's disease are most prominent when your hands are at your sides or resting in your lap.