Strength of mind rests in sobriety for this keeps your reason unclouded by passion.
Maturity - among other things the unclouded happiness of the child at play who takes it for granted that he is at one with his play-mates.
I have one brother John an airline pilot who is seven years younger. He's adopted though we're still blood related - he's my cousin. My parents couldn't have any more children after me so when Dad's brother died they adopted John then just a baby.