Not because they don't know it's harmful; most do. Because the forces that drive initiation operate at a level where health knowledge has almost no influence.

Once, specifically, and from the right position because the wrong conversation about smoking with a teenager produces the opposite of the intended effect.

Most smokers initiate between the ages of fifteen and nineteen, with the average age of first cigarette falling between fifteen and seventeen in most countries, including India. Almost no one starts smoking as an adult.