Sibling Legacy

My brother goes to Yale. Is sibling legacy considered legacy for admissions purposes?

See: http://talk.collegeconfidential.com/yale-university/1818697-sibling-legacy.html

My understanding from the AO is that it is infrequently considered. It is definitely not viewed in the same light as a parent legacy. Yale does include children of graduates of the professional and grad schools as legacies.