Voting, moving out, getting medical care, and marriage generally don't negatively impact your body and brain.
Alcohol, weed, cigarettes, etc. all do some kind of damage to your body. If anything we should raise cigarettes to 21. And yes, even weed, especially smoking weed, does damage to your body, even if it's massively less than the other two I said.
(And getting drafted... well that should just go away all together).
