This 100%. AT 13, I was legit still playing with my Charlies Angels dolls, and bopping to my disco records in my bedroom. I was not a mature 13 IYSWIM. I was just a kid... I was 13 and I acted 13! I didn't really know what sex was at that point. I mean I kinda had an idea, but didn't know much. (Had biology lessons but it was very vague and basic.) I also did not WANT to know.
Had my first proper kiss at 16-17, and had sex first at 19. I think I may have said 20 yesterday, but I worked it out in my head properly and it was a certain summer just after I had turned 19. And it was a boyfriend who I had been with for 5 months (a long time when you're 19!) He was 3 months younger than me.
However... I know some girls DID have sex at 12, 13, and 14 when I was at school. (in the 1970s.) Including a couple of my cousins and neighbours. Many girls who started young ended up having kids before the age of 17-18, and some have not had the best sexual health experience, or even general health experience. I think 'having sex very young' is sometimes linked to health issues. There is a well documented link between having multiple sexual partners young and certain health issues.
Many of the girls who started young, carried on having sex with many different males before they were 16. One girl I knew at school bragged about having shagged 20 different men before she was 15.
The girls I knew at school who had sex very young, always seemed to do it with older males too, the males were never the same age (12 to 15,) they were as old as 19-25. The girls thought they were so cool and edgy having sex with a man of 22 when they were 14! Horrifically it seemed 'normal' then. A few girls had sex with men employed by the school - cleaners and caretakers, and random blokes in the area - including fathers of some of their schoolmates. It was all very 'Rita, Sue, and Bob too.' Utterly dreadful.
I have 2 DD, both late 20s now. They were both almost 20 when they lost their virginity. Had left school and college and were at uni. The thought of them having sex at 12-13 just fills me with horror. They were CHILDREN. Like me, they were just enjoying their childhood, and weren't looking to have sex at 12 or 13!
.