code: public Family createFamily(final String idString) {
          if (idString == null) {
              return new Family();
          }
          final Family family = new Family(getRoot(), new ObjectId(idString));
          getRoot().insert(family);
          return family;
      }
docs: Encapsulate creating family with the given ID.
  
  @param idString the id string for the family
  @return the family