Make Beer and Wine Legal for 18 year olds

In America, we have no problem letting our 18 year olds fight for our freedom, why cant they have a drink? Its because the government has set the minimum age as 21. Why such an odd number? Its because science says the human brain is not fully developed until the age of 21. Now it's understandable to not let 18 year olds to be taking shots and getting wasted, but is it so bad to let them have a cold one? Yes beer and wine are still alcoholic beverages and can still get you drunk, but its a lot harder and it's not as likely. The legal age to buy and consume beer and wine should be set to the age of 18 years old.