Выводит не все строчки ответа (Turbo Prolog)

predicates
 parents(String, String)
 man(String)
 woman(String)
 sister(String, String)
 brother(String, String)
 father(String, String)
 mother(String, String)
 grandfather(String, String)
 grandmother(String, String)
 print
clauses
  parents("Tom","Ellen"). 
  parents("Tom", "Chris").
  parents("Jane", "Ellen").
  parents("Jane", "Chris").
  parents("John", "Jane").
  parents("Eve","Tom").
 man("Tom").
 man("Chris").
 man("John").
 woman("Ellen").
 woman("Jane").
 woman("Eve").
 
 sister(X, Y) :- parents(Z, X), parents(Z, Y), woman(X), X<>Y.
 
 brother(X, Y) :- parents(Z, X), parents(Z, Y), man(X), X<>Y.
 
 father(X, Y) :- parents(X, Y), man(X), X<>Y.
 
 mother(X, Y) :- parents(X, Y), woman(X), X<>Y.
 
 grandfather(X, Y) :- parents(X,Z), parents(Z, Y), man(X), X<>Y.
 
grandmother(X, Y) :- parents(X,Z), parents(Z, Y), woman(X), X<>Y.
print:-sister(X,Y), write(X,"- sister -", Y), nl, fail.
print:-brother(X,Y), write(X,"- brother -", Y), nl, fail.
 print:-father(X,Y), write(X,"- father -", Y), nl, fail.
 print:-mother(X,Y), write(X,"- mother -", Y), nl, fail.
print:-grandfather(X,Y), write(X,"- grandfather -", Y), nl, fail.
print:-grandmother(X,Y), write(X,"- grandmother -", Y), nl, fail.
print.
GOAL
    print,
    readln(I).