I grew up in a small town where I could get up at 8, shower, have a quick breakfast, and still be at school by 9. So I thought 8 was the norm. When I was studying and teaching at university I tried not to have any classes before 11 so I got up even later.
When I moved to LA I discovered I had to get up by 7 just to get to work on time. (When I'm on a film it's more like 5:45 or earlier.)
So now I usually wake up between 6:30 and 7 and get out of bed at 7 or a bit later, but that still seems early to me. I think our concept of norms is set when we're young.
My kids had to be at school by 8 and sometimes earlier, though supposedly teenagers' natural rhythm is to get up later.