Only this year have I started seeing R-rated films myself, and so far I haven't really seen any children in my screenings (though a big reason for that was because most of them are in the late morning/early afternoon). My screening of Blade Runner 2049 was mostly older people, I was probably one of the youngest people in the theater (if not the youngest).
On the flipside, there has been a few times my mom took me to see an R-rated film in the theater when I wasn't seventeen yet; mainly for films she was interested in seeing. One or two of the films scenes usually had a scene that got me a bit shook up, but otherwise I wasn't really fussed.
