Dad, this is none of your business! You never had sisters or brothers to fight. And you stand abashed   again, an only child. Lone species from two multi-sibling parents who found you a mystery.   You can be made an only child by rivals who fail early and give back your lullaby.   You can see sibbling taught by the instant rally of a cohort that, were you theirs, would defend you   though with the same giggles about bossiness or dalliance— You do have brains, but no sense!   Employable only solo or top, making friends from…