The third birth cohort, those born in the late 1940s to the mid-1950s, entered young adulthood as the health risks of smoking were becoming clear. The evidence provided by the scientific community created controversy over the dangers of smoking but left individuals to weigh the costs and benefits of starting or continuing the habit. Changes in smoking should be most evident among social smokers and least evident among those for whom smoking is genetically oriented. That is, those for whom quitting is easiest will be the most likely to quit in light of the evidence provided by the Surgeon General, leaving the population of smokers to be composed primarily of genetically vulnerable persons. Thus, the genetic influences on smoking will once again increase. Dominated by a drop in social smoking, this increase is again consistent with the social push model.
