so many interesting points of view.
Custardo totally trivial, off topic question but what sort of school uniform haspon to be ironed every night? No wonder you say no way!
anyway back to topic. To me it boils down to a belief in the power of unconditional love.
I am an only child. Both my parents are dead. They loved me unconditionally - I felt that love all the time. It was like no other love. Couldn't compare to the love I got from from friends or lovers. It was family love. I don't know if siblings give each other unconditional love as I am an only child. I like to think they do. The whole blood is thicker than water thing.
Right now I feel there is no one to give me unconditional love - my husband loves me, but he chose me. The sheer act of choosing me means his love for me is different. There are expectations from him to me and me to him. I can visualise me doing something awful and him stopping loving me. I could never visualise that with my parents. My children give me unconditional love, it is true, but as they are children, they are at the taking more than giving stage - I cannot lean on them. I can just look forward to that love growing. My husband's parents say they love me, but however nice they are to me, they love me on certain terms. I expect if dh and I broke up and dh was distraught, they would side with him against me. So my children are my only source of unconditional love.
I think, if I had a brother or sister, there would be someone else in my life who loves me unconditionally. I wanted my son to have more chance of unconditional love throughout his life and that was a major reason why I had another child. I wanted some part of the family my son grew up with to be there for him in his old age. In a way it's an extension of the reason for having an heir and a spare. That point about having two children so if one dies, one is left, well in my opinion that holds true for whole families. It is what happens to us all.
Families die - mine did with the death of my parents. I have joined a new one and there is lots of love in it. But with no brother or sister to remember my first family with me, my life will always be divided into two parts. One family died and one family was bought to life. My first family gave me unconditional love and my second family give me conditional love.
Do siblings love each other unconditionally if things don't go wrong? I feel they must do, as they did not choose each other. Am I painting too rosy a picture of sibling bonds? I don't know. I am sure in bigger families, with lots of aunts, uncles and cousins, there is far more unconditinal love sloshing around, far more chances of shared family memories if the extended family is close knit. In that case having an only child is not such a big deal.
It was a real struggle to go back to have another child after my first and we nearly didn't do it. But for me it is so important that our son does not outlive all his first family and lose all our unconditional love.