In a recent study, more than 1,300 men and women in the UK over 16 years of age were asked to identify those events in life that represent transition into adulthood.
Regardless of age, the participants identified five important measures of adulthood:

-accepting responsibility for the consequences of actions;
-deciding on personal beliefs and values independently of parents or other influences;
-achieving financial independence from parents;
-becoming less self-oriented, and developing greater consideration for others;
-avoiding drunk driving.

I couldn't make this up if I tried.