My parents went back and forth on this. I watched Conan the Barbarian (VHS rental) with my parents when I was 5 or 6, but didn't get to see Terminator until I was in middle school because it was "too violent."
Plus, most of the movies we "owned" were taped off of cable TV (we only had it in the summer, when the Disney channel would do free month promotions. I guess there were no year-long contracts back then.) and edited accordingly. So I watched "Alien" when I was a fairly young kid, but didn't
watch Alien until college.
I did see
this at 14. It was neither my first rated-R movie nor the first movie I had seen with nudity.
My mom in particular had a preference for older movies, as well. Given the Hayes code and the singular viewpoints that were pushed in the '40s and '50s, there were a lot of "serious" movies that were, by the late '80s and early '90s, pretty fucking laughable, and somehow I knew it.