If you received free cigs just like your buds, why don't you have lung cancer? Could it be that exposure to some other element or combination of elements, plus genetics caused their lung cancer?
Those smoking 25 or more cigarettes a day have a 25x greater chance of lung cancer than non-smokers.
I quit right after getting out of the service and have remained smoke free for years. My dad smoked for decades, but he didn't die young from lung cancer, but his wife did. He died of a massive heart attack. The smoking was the cause, according to his medicos. Lung cancer does appear to have genetic tags and exposure to all kinds of other irritants can also exacerbate the problem.