They were seen as biologically distinct due to their larger noses, used for filtering out impurities in the air they breathed; Self-cleaning lungs, again for impurities; Extended index middle fingers, for the proper handling of Cigarettes; Smaller ears, due to an evolved habit of not listening; Extra eyelids, that protected their eyes from irritating smoke; and an in-built resistance to heart disease, lung cancer, and thrombosis.
The species was also known for their incredible pallor, and for living in toxic environments in which no normal human could survive, able to breath the toxic smoke emitted by various flying vehicles that often coalesced into smog. As a result, they usually lived near the bottoms of advanced cities, in the slums.
The Natural Born Smokers were recognized as responsible parents. They promoted early education, via exposing their children to tobacco smoke from birth. When the child grew old enough, they would be sent to a form of school, to be taught the correct way to inhale cigarette smoke, by a group of people known as "friends." Any of the children who resist, seeking not to smoke the cigarettes on any grounds, were often ridiculed until they complied. The children would develop a fully-fledged nicotine dependency, and the cycle would carry on.
The Natural Born Smoker does not develop in every multiverse, for various reasons, many of which involve either the advancement of society and the abandonment of cigarettes, or on a less positive note the end of humanity. It is a dark world indeed where the species arises.