Beginning June 8 in California, you have to be 21 to buy cigarettes and other tobacco products. That is, unless you’re active duty military. Military personnel can still buy cigarettes at age 18. Those men and women can go to war, after all, and if you’re male, you must register with the Selective Service on your eighteenth birthday. We all become adults when we turn 18, don’t we? Well, it depends on which benchmark you’re looking at, and which state you live in. And though we generally think of our eighteenth birthday as the day we transition to adulthood, that hasn’t always been the case.