From the Latin manus , hand.
Nothing prevents our being natural as the desire to appear so.
Even the stupid can succeed if well-mannered. Voltaire Drowning would improve a lot of people's manners. That is, it may be proper and polite to belch after a meal when hosted by the inhabitant of a distant culture, yet it's likely considered rude where you live now. Hence, proper etiquette in each of these situations, while perhaps consistent for a geographic region, varies widely around the world. Your hostess may serve meat, for example, unaware of your avoidance of meat on moral grounds.