I am 38, an only child to two wonderful parents.
They desperately wanted more children but had fertility issues and it took them an age to just have me. They were unable to have any further children.
As I get older, I am finding myself more and more upset about being an only child. Seeing how well friends get on with their sisters, having support if parents get ill and when they're old and you're having to sort out their affairs etc.
I have cousins, but I am not close to them. I am married and have children of my own, but I really wish I had a sibling.
I am close to my parents and of course I worry about when they're not here anymore.
YABU - being an only child is great/suck it up buttercup
YANBU - it is hard and can be lonely