Mortality in Smoking Discordant Monozygotic and Dizygotic Twins

Abstract

Among 706 male, dizygotic, smoking discordant twin pairs born in 1901 to 1925, 13 deaths occurred among nonsmokers or less exposed partners against 34 among smokers or more exposed. In 246 corresponding monozygotic pairs the figures were 14 against 9. The excess mortality among male dizygotic smokers was not associated with any specific cause of death. Four cases of lung cancer among males occurred only in smokers. Accidents and suicides seemed to be associated with smoking, supporting the hypotheses regarding differences in personality typebetween smokers and nonsmokers. Only time will show whether trends found are stable. The data suggest, however, that part of the greater mortality in smokers is not due to smoking per se but to factors associated with smoking.