Raised a stepson starting in 1980 (he's 38 years old now and own a multi-million dollar construction company)
Raised a stepdaughter with my second wife starting in 1990
I currently have two daughters.
I was also (just as you were) a kid myself. And I can flat tell you that some people mature a lot faster than others. I've known MEN that were 15 years old, and I've known KIDS who were 30.
There is no "one size fits all".
My personality was pretty much formed by the time I was 12. Not saying that I was a man yet. But my thinking processes and general personality were the same then as they are now. At least the "voice in my head" has been the same one since then.
As a guy who turned 18 in 1979...I can tell you that 18, 19, and 20 year old ADULTS are treated MUCH differently in the United States than they used to be.
When I was 18 I was treated as an adult in every way.
Today? An 18 year old is a child. They can't even go to a nightclub and learn how to socialize for God's sake.
The result? Our country is full of socially retarded 21 year olds who don't know how to hold their drink and generally are clueless.
Fuck. By the time most people are 21 they are already knee deep in marriage and a baby. And they STILL haven't been treated like an adult.
Our society calls them "Children" and by God that's the way they act. I coudn't believe it when I heard that people were happy that they could keep their "kids" on their health insurance until they are TWENTY SIX!!!
WTF!?!?! No wonder people these days have no sense of responsibility or any ambition or drive.