I was 22 when I went to my first movie. I felt it was "safe", since I had just moved to Alaska, and Dad was back east. 5,000 miles between us seemed like a reasonable distance so that I wouldn't get in to trouble. And... guess what? The ceiling didn't fall in on me!! Go figure.
One of my favorite directors/screenwriters didn't see a movie until well into his teens -- strict calvinist upbringing.
I'd be interested to know if you think it's influenced your taste in movies...