father(terach,abraham).
father(terach,nachor).
father(terach,haran).
father(abraham,isaac).
father(haran,lot).
father(haran,milcah).
father(haran,yiscah).
female(sarah).
female(milcah).
female(yiscah).
male(terach).
male(abraham).
male(nachor).
male(haran).
male(isaac).
male(lot).
mother(sarah,isaac).
son(X, Y):- father(Y, X), male(X).
son(X, Y):-mother(Y, X), male(X).
daughter(X, Y):- father(Y, X), female(X).
daughter(X, Y):-mother(Y, X), female(X).
grandfather(X, Y):- father(X, Z), father(Z, Y).
grandfather(X, Y):- father(X, Z), mother(Z, Y).
grandmother(X, Y):- mother(X, Z), father(Z, Y).
grandmother(X, Y):- mother(X, Z), mother(Z, Y).
grandparent(X, Y):- parent(X, Z), parent(Z, Y).
parent(X, Y):- father(X, Y).
parent(X, Y):- mother(X, Y).