While it is limited, there is evidence for genetic influences on route of administration. One twin study identified variations in the extent to which heritable factors influence tobacco use by route of administration. Genetic factors explained 16% of the variance in cigarette smoking and up to 73% of the variance in dip (smokeless chewed tobacco) use while they were found to have no appreciable impact on pipe and cigar use (75). Thus, it is possible that the influence of a shared route of administration is partially governed by genetic factors.
