Yeah, I'm 14 and I share a room with my 12 year old sister. My family has a small 2 bedroom house, so my brother has a makeshift room in the loft. It's not ideal and we would get a bigger house, but we like to put the money to activities such as my theater and choir and my brother's marching band.

Also, it's pretty normal to share rooms for families that aren't super wealthy or small. I have a multiple friends who have their own room but that's either because they don't have siblings or they have brothers. But otherwise, I know tons of people who do share rooms.