predicates

    father(symbol,symbol)
    mother(symbol,symbol)
    male(symbol)
    female(symbol)
    sister(symbol,symbol)
    brother(symbol,symbol)
    uncle(symbol,symbol)
    wife(symbol,symbol)
    aunty(symbol,symbol)
    bhabhi(symbol,symbol)
    cousin(symbol,symbol)
    nephew(symbol,symbol)
    grand_son(symbol,symbol)
    grand_duaghter(symbol,symbol)

clauses

    sister(X,Y) :- father(X,A),father(Y,A),female(Y).

    father(dhanjiBhai,vithhaldas).
    father(chuniBhai,vithhaldas).
    father(harshad,dhanjibhai).
    father(darshan,dhanjibhai).
    father(nilam,dhanjibhai).
    father(kiran,dhanjibhai).
    father(kamleshbhai,chunibhai).

    mother(harshad,prabhaben).
    mother(X,Y) :- father(X,Z),wife(Y,Z).

    brother(X,Y) :- father(X,A),father(Y,A),male(X).

%    brother(X,Y) :- brother(Y,X).

    male(harshad).
    male(darshan).
    male(dhanjibhai).
    male(chunibhai).

    female(nilam).
    female(kiran).
    female(prabhaben).
    female(nimishaben).
    female(kokilaben).

    wife(prabhaben,dhanjibhai).
    wife(nimishaben,kamleshbhai).
    Wife(kokilaben,chunibhai).


    grand_son(X,Y) :- father(A,Y),father(X,A),male(X).
    grand_duaghter(X,Y) :- father(A,Y),father(X,A),female(Y).

    uncle(X,Y) :- father(X,Z),brother(Y,Z).

    aunty(X,Y) :- wife(Y,Z),
              brother(Z,W),
              father(X,W).

    bhabhi(X,Y) :- wife(X,Z),cousin(Y,Z),female(X).


    cousin(X,Y) :- father(X,A),father(Y,B),brother(A,B).

    nephew(X,Y) :- wife(Y,A),brother(A,B),father(X,B),male(X).