Q. I roll my own cigarettes, and I’ve always believed that doing that lowers my risk of cancer. That’s because it takes so much more time to prepare them, and there is less tobacco in each cigarette. My doctor tells me that isn’t true. What do you think?

A. I agree with your doctor. You probably smoke your cigarettes into a smaller butt than smokers of bought cigarettes. Norwegian doctors have shown that people who rolled their own for years were more likely to develop cancer than those who bought cigarettes. You remind me of the people arguing about the best bit of the Titanic to hold on to when it was sinking. If you take tobacco into your body, you steeply raise your risks of all sorts of diseases – regardless of how you do it.