re: family group
Even though the Geni default is to define your "Family Group" to be 4th cousins (with the implicit 4 grand-parents), you can restrict your "Family Group" to be less than that -- and it does restrict those "outside" that scope you define from "seeing" inside that 'boundary'.
See how at your Family Groups under your Account Settings (under your name in the upper right corner): here: http://www.geni.com/account_settings/family