According to a recent internet article:
A recent study published online Tuesday found that smoking can damage the DNA permanently. altering nearly 7,000 genes that can contribute to the development of smoking-related illnesses.
The American Heart Association’s journal Circulation: Cardiovascular Genetics found that smoking leaves its “footprint” on the genome through DNA methylation, the process by which cells control gene expression.
According to the Centers for Disease Control and Prevention, nearly 40 million adults in the country smoked cigarettes. Cigarette smoking accounts for one in every five deaths or over 480,000 deaths every year in the United States.
See: http://www.ibtimes.com/smoking-leaves-permanent-footprint-human-dna-study-finds-2419660
