>>>I think 25's about when personalities stabilize.
I was married before 25. I don't think a personality stops stabilizing. You never stop experiencing new things. You adjust as you go.
So you wouldn't want MIL enlisting until 25?
Eighteen is good for soldiering, so if we're going to use them that way then we owe them full adult status as a matter of basic fairness. In fact, I'd say that the same 'basic fairness standard' requires us to give adult status to anyone we expect to pay taxes -- which is everybody. As a practical matter, though, the country would be a little more responsibly governed if the voters were all 25 or older.
I'm not especially conflicted about this; it seems to be a situation where there is no ideal solution but none of the alternatives is all that bad, either.