My only encounter with a romance novel that I didn't know was a
  romance novel (by some) was Clan of the Cave Bear. I was in 7th
  grade. Human girl lost among more primitive humans. Got
  scratched. Taken care of by tribe of proto-humans of some sort.
  They had different sex ways but I was 12/13 yrs old and figured,
  "Ok, that's probably how they did it back then" although I
  laughed out loud at things like, "throbbing member" and stuff
  like that. I was like, "Oh come on, REALLY!?!" Told one teacher
  about the book. She was very interested that I knew about it and
  liked it and we're talk about it. [all the not-cave-sex stuff of
  course]. Another teacher I told got really mad at me. "What are
  you reading that smut for? doesn't your mother know what you're
  reading?" That's when I figured it out.