What do children without brothers and sisters lack psychologically?

Not only will I not lack anything, but I will also have more love ~ ~ I have brothers and sisters at home, and I love them very much ~ I am glad that I am my sister, and I will take care of them ~ ~ ~

Don't people depend on themselves? Why should they rely on others and be protected by others? Besides, aren't there parents who love you ~

You don't need to let yourself fight for what you want ~