Ideally, each person should have their own bed. Perhaps that's even a reason for the invention of bunk beds. A way to put more people into less space for less cost. Sharing beds can lead to "awkward" situations. But I do not believe in humans using either "birth control" nor population "control." No doubt, there are numerous examples that can be listed in which there, at times, may get to be more people around, than beds for them to sleep in. Generally, in such a innocent situation, I am okay with sharing beds. I would rather share a bed, than pay extra for my own private motel room, on a trip. And I do believe that families should continue to grow naturally, even when every single bed and bedroom is full-up of people. Especially younger siblings of same sex, can share a bed. Far better to "share" and for humans to populate up closer and denser, than to ration unnaturally the number of human lives that can be experienced at the same time.
I don't prefer to sleep on the floor needlessly, nor to "fight" over beds. And who really needs a lot of space really, merely to sleep?
Yes, I have shared a bed before, but very rarely, perhaps only once if I recall right? Did nothing but sleep, and turn in the opposite direction. | 
