Frankly, I don't believe in favoring the kids of alumni, perhaps the siblings, just because it really hurts to get a No from the school who accepted your older sister 2 years earlier.
My son was rejected from my alma mater, despite the statistics saying he was twice as likely to get in as someone without an alumni parent.
I wondered though.... do schools differentiate between large contributing alumni and alumni who contribute little or none? Sounds like they do based on the Yale guy's quote about having rejected more children of some category of alumni donors. So he knew the statistics not just based on alumni, but on big buck alumni versus not. As though Yale really needs any more money in their alumni fund. Seriously?
But just in general -- do you even want, as a student, to think that you got your spot at a very competitive college because of your mom or dad? I don't think so.