Your situation is irrelevant to your younger siblings anyway. Had you applied last year or next year, you may not have gotten in. Also, decisions are made based on all aspects of your application. It is probably not just one aspect that nailed it for you. and, if one thing changed, but any one thing, the outcome could have been different. So apparently your application all worked together in a way that resulted in an acceptance. Would you have been admitted with slightly lower scores? Who knows? Not even the adcons who advocated for you could tell you that.