This must be such a generational thing. When I was growing up, I hardly knew anyone who didn't share a bed with a sibling, at least for part of their childhood. I shared a big bed with my younger brother until I was about 14, at which point we finally got bunk beds. I remember a family friend helping my mother set them up and joking with us kids that we should feel lucky she was indulging us.

Having one's own room was a big deal, because it was relatively rare.

How times and norms change!