We are a single-sex (all girl) school with an associated, but separate, brother school, but we do take into consideration legacies from the brother school and we have had to lump both schools together when asking about legacy connections--although they don't carry the same weight. With many uni-sex names now, it would make it easier to know if the legacy is a brother, it's a legacy from the other school without having to search back through alumnae records.
Chiming in, it's strange/inconsistent that some relationships have gender split options (spouse, husband, wife), but most don't. For some this is fine (ex we don't necessarily need someone marked as "father" vs "parent", "brother" vs "sibling" etc, especially if we have their gender), something like "Aunt/Uncle" should really be separate options - these relationships often are used for Emergency Contacts, and it looks off to have a contact listed as "Aunt/Uncle".
Consistency is really a big issue with this (a recurring problem we're encountering with features in Blackbaud products...). Have gender-split options for all relationships, or none. Or, more ideally, allow us to add to/edit relationships - the less that's hard-coded, the better.