Tim Allen wrote a book years ago, titled something like "Don't Stand Too Close To A Naked Man".
It was basically sorta-autobiography, sorta random-musings, sorta parts of his stand-up-act, all mixed in with his DIY-guy stuff, like finally earning enough to buy a riding lawnmower, and being able to afford the optional hubcaps!
Anyway, in that book, he details, sort of, his discovery of the opposite sex. As a kid, one of his friends had an older brother, who had put up a Playboy centerfold in his room.
At some point Tim and his friend needed to go into the older kids room to get something, and Tim spots this pin-up.
Now, Tim Allen of course is like in his sixties now, so this would have been sometime IN the sixties. So the centerfolds of the time were more "Vargas girl" and less "gynecological close-up" that they are today. (Or, that I'm told they are today. )
But, she was still very much topless, and in the book, Allen notes that was the first time he ever realized there was a difference. He'd seen his mother naked before, but this was different- he said he realized the girl was naked for a reason. There was a purpose to her nudity.