When does growing up begin?  When do we start becoming adults?  I don't mean
physically, I mean when someone says "hey man, grow up!" that kind of
"growing up".  Acting more mature, thinking about adult things like world
affairs, politics, the finer details of interpersonal relationships  
including friends, family, romantic, etc...?

When I was a teenager, one of my main socializing outlets was BBSs.  There was
rarely anything resembling age verification.  People who got on BBSs were 
connected to other people and of all different age groups.  I was talking with
adults, older teens, and people around my age.  

Being a teenager, I'd say stupid things and I would utterly lack knowledge 
that the adults took for grantid.  But this is how I learned.  When I said
something stupid, someone with more years and wisdom would let me know it, and
I was better for it even if a little embarrased.  I was not drawn into a 
bubble of like-minded BBSers that thought & felt what I thought and felt.  I
was not fed what the system thought I wanted to read.

I suppose my situation is not normal.  I suppose most families today probably
have extended family around them; aunts, uncles, grandparents, cousins, 
friends of the family etc...  Adolscents can pick up things from these people
IRL outside of the online world and that's great.  So many this whole post
only applies to people in the same situation I was in growing up.  That is, 
extended family is hundreds of miles away, you see them once or twice a year,
and you're really just around your parents and a coupld siblings.  

Today, open a certain site (like a social media platform) or maybe a certain 
app, it wants to know, generally, how old are you?  It wants to tailor your
experience for your age bracket.  What it thinks is safe to expose you to.

I get that the internet has predators on it.  I get that it's an unsafe place,
and if I had children and they were online I would be terrified of who they
might be talking to.  But at the same time had my parents been terrified of
who I was talking to on bulletin board systems in the 1980's then my growth
into mental maturity would be much more stunted because my exposure to adults
and their ways of thinking and the things they know about the world, jobs, 
politics, hell even just simple things like how investing works or how to fix
a car.  This would all have only started once I turned 18.

Of course you learn from your parents but to only learn from these two people
and no one else is very limiting.  Plus some people (not me) have terrible
parents and would be better off *not* learning from them.

Worse yet, if my starting to become adult (mentally) only started when I was 18
then I would not be prepared to be a mentor for others up-and-coming adults 
for the next generation.  Over time the whole society would tend toward 
childishness.  

It would be a world ... well, a world very much like the one we see today.

Adolescents will not begin to think like adults until they are interacting 
with adults.  If they are shilded from adults until their 18th birthday, by 
then they've already falled into the gravity well of their own social media
echo chambers and will have to activly try to climb out of it and force 
themselves out of their comfort zone to interact with people they've never 
been exposed to, to thoughts and ideas that's completely alien to them.  Few
will know to do this, fewer still will have the will to do this, fewer still
will succeed in doing this.
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