Since my first exposure to the Romantic poets in junior high, expressing myself through writing has felt essential. And if not for the early encouragement my two sisters gave my pathetic adolescent poetry, it's unclear if I'd still be at it a half century later. Who in your early life gave you that kind of creative support?
Many writers of note speak of their "ideal readers" - people they want to reach above anyone else. My sisters are ideal readers for me although not only because of their lifelong support. Along with my wife and oldest niece, both are among the most avid readers I know. Love of reading makes any feedback about writing more meaningful. Stephen King once commented that pointed criticism of his writing stung much more whenever he was certain the critic was read widely. Several years ago, I picked up Stephen Sondheim's memoir "Finishing The Hat" based on a review written by Paul Simon. I'll guess Simon's feedback meant something to Sondheim because the two share an obvious love of and talent for music. The value I place on my sister's opinions of my writing, notoriety aside, is based on a mutual love of the written word.
A brother as a musical MVP and two sisters as ideal readers. I've got this sibling thing nailed.