posted by Valerie .
We must truly become our brothers’ and sisters’ keepers.
Is this written correctly? OR should it be
We must truly become our borther's and sister's keepers. OR
We must truly become our brother and sisters' keepers.
Because the statement applies collectively to many people (we), the group to which it applies will presumably have many brothers and sisters. Hence the plural possessive use of the apostrophe (choice #1) is appropriate.