The relationship between young men who smoke show changes in the Y Chromosome suggesting a causal relationship between the appearance of earlier lung cancer in young men than comparable men of the same age. Lung cancer has been known to have a higher in men than women, so this relationship is important. The changes can be measured in the red blood cells of smoking men. This article was published in the prestigious journal Science.
Article: J.P. Dumanski et al., “Smoking is associated with mosaic loss of chromosome Y,” Science, doi:10.1126/science.1262092, 2014.