This is a bit of a hypothetical post since I'm currently only 21+5 with DD1 (and have no other DCs). But DH and I are hoping to move home before the baby is born (or shortly after
) and whatever we buy we are likely to be stuck in for a long time (low/negative equity situation). So we want the house to be somewhere where, in the worst case scenario, we can happily knock off as many sprogs as we like 
I mentioned this to SIL and said we were looking for somewhere with 3 bedrooms (we currently have 2) so that even if we had several kids boys and girls could share a room.
This is a massive step up from my own childhood, where I shared a room with my brother until I was 14 (he was 11), after which he got put in a cupboard knocked into a wardrobe (a la Harry Potter) and I shared with my new step-sister until I was 17 and got my own room.
DH has 3 sisters (of which SIL is one) and he had his own room while the three of them shared.
Anyway, SIL was horrified and said children shouldn't be made to share rooms and that it was hell sharing, even with 2 sisters she loves to bits. She thinks it's only acceptable until they're 8 or 9, after which each child needs its own room. (I am sure she will revise this once she has her own children and can't afford a room for each of them!)
But it got me thinking - what is acceptable for sharing and what isn't? Does anyone agree with SIL? Isn't there a law about boys and girls sharing? I had been naively hoping that sharing would be a good thing, even if it went on into the teenage years, because it would be nice to share with a sister (after years of a brother), and might stop some of the hovelling-away-in-your-own-room-and-chatting-to-men-on-the-internet scenarios, etc! Now starting to think I'm wrong and that the ideal scenario would be each to their own. What do other people think?