I like this definition.  Anecdote time.<p>My great-grandfather left his home at the age of 12 to work in a coal mine and send money home to his mother.  I&#x27;d say he was as much an adult as any college grad today.<p>My wife&#x27;s grandpa managed a dairy farm.  He got sick once when my wife&#x27;s dad was 10 years old.  Her dad milked the cows so her grandpa could rest and get over his illness.  He hasn&#x27;t stopped milking cows twice a day for <i>50 years</i>.  I&#x27;d say he was an adult at 10.<p>My dad was taught to work like a man from an early age, but was also taught to drink to excess.  I remember when he got his last DUI.  I was about 11 years old.  I&#x27;d say that was when he finished growing up.<p>The dividing line between childhood and adulthood for me is a total blur between the ages of 18 and 28.