My earliest sex education (pre-CSA) was my father's Playboy magazines. In the 1960's they used a technique called "airbrushing" to erase the models vaginas, so it looked like there was just nothing between their legs at all. Of course all that changed in the 1970's, and now with the internet....holy cow!
Consequently, I had no idea what a guy would do with a girl besides look at her breasts. My pre-teen sexual feelings were aroused looking at them, but did girls have those feelings? It never occurred to me. At that point I thought sex was just looking at "dirty" pictures in Playboy. Put my penis inside a woman's body? GROSS!! Besides where would you put it?
Of course all that changed a few years later when my understanding of sex was forever twisted by the nice man who invited me into his house and gave me drugs and alcohol, and then......
"Carry on my wayward son
There'll be peace when you are done
Lay your weary head to rest
Don't you cry no more"Kansas