Quite a few threads recently on parents worrying about not giving their child a sibling / feeling guilty about their being an only child. As an only child looking back - can I please just say to parents - don't feel guilty. The most popular girl in my class was an only child.
I was an only child, and being an only child didn't affect me adversely- I didn't necessarily want company in the school holidays or anything. What really smashed my self confidence to smithereens was my mum trying to force/coerce friendships and calling me selfish when I wouldn't go along with it. So in other words what adversely affected me most was mum not letting me be my own person and this could easily happen to children in large families. What I'm trying to say is don't worry or feel guilty - objectively speaking - it's fine to be an only child - they really are no different as a whole from people with siblings - this is my experience anyway!