I wonder what kinda dystopian society you guys lived in lol. When I was in my early teens, I was playing basketball and hanging out at the mall. Of course, I was taking baby steps into the lewd world out there like everyone else, but drugs, sex, and alcohol? What the fuck. That's high school stuff for the majority of people. There are always outliers, but yall talkin like it's the most normal thing for preteens to do all that shit.
Like with so many topics, it is really difficult to get from only your personal experience, some gossip/embellishment and your overall environment to a general statement.
I remember me being ~16 when I was first interested in adult stuff at all, but I was a late bloomer.
Stuff like 'who loves whom' and teasing your peers about it was already present when I was 13.
(switch from elementary school to the next level between 12/13)
The first time a friend of mine from school had a girlfriend we were around 18 (most of us were 19 at the end of school), and up to that point we were playing Tabletop RPGs and Warhammer 40k like every week for ~5 years, so no one would have had time for that without someone noticing.
We were no nerds, but also not part of any IN clique.
One of those friends (who was at the same elementary school as I) told us that they had already been kissing in school breaks when they were 11-12 - they were SO mature - still nothing happened until the end of school.
I later had a colleague that told me on the boarding school he had been at a girl offered him sex if he rode the bus to school with her when they were around 12. He also said that when he was 18, he already had had enough of sex after his activities of the previous 6 years.
This was during the late 90s and early 00s. And the experiences are VASTLY different.