Lower the drinking age to 18

I, like many others, are fed up that the government has the drinking age set to 21. When you turn 18, you can enlist in the military and die, buy cigarettes and vote, among other things, but you cannot have an alcoholic beverage until 21. It makes no sense to me what so ever, so I decided to write a petition to lower it to the age you are legally considered an adult in America. Most of Europe tends to favor that when you become 18, you're an adult and you can do what you like beit drinking, smoking, enlisting or voting. It makes no sense that we have to be different from every other developed nation for no reason.