I was middle of 3, but the house was always full of itinerant adults and their children, Embassy staff who were experiencing British family life, au pairs from anywhere and everywhere, as well as relatives. I have a ridiculous number of first cousins who would often be sent to stay with us during the holidays, or we with them.
As a child, the really important unit was me and my brothers. I think we were very close at least partly because the house was so full of other people, and though most of them were great, and having other children our sort of ages about was good (one lot stayed for over a year, none were with us for less than 6m), they were not permanent.
I can't say that I enjoyed being part of it all. It was normal. That was how life was. As an adult I can see advantages and disadvantages.
If you have a big family - ie, lots of siblings - then you have to have a way of gelling them all together, which, from seeing some of my uncles and aunts, is not as easy as you may think. Some have done it fabulously well, but not all by any means; and when it goes wrong it does seem to be specatacular and pretty permanent.