Stuff

father(Father, Child) :- man(Father), parent(Father, Child).
mother(Mother, Child) :- woman(Mother), parent(Mother, Child).

child(Child, Mother, Father) :-
             woman(Mother),
             man(Father),
             parent(Mother, Child),
             parent(Father, Child).

man(Man) :- \+ woman(Man).
woman(Woman) :- \+ man(Woman).

is_father(Father) :- father(Father, _).
is_mother(Mother) :- mother(Mother, _).
is_child(Child) :- child(Child, _, _).

are_siblings(Child, Child2) :- parent(Father, Child),
                               parent(Father, Child2),
                               parent(Mother, Child),
                               parent(Mother, Child2).
are_brothers(Child, Child2) :- are_siblings(Child, Child2),
                               man(Child),
                               man(Child2).
are_sisters(Child, Child2) :- are_siblings(Child, Child2),
                              woman(Child),
                              woman(Child2).
                              
uncle(Uncle, Child) :- man(Uncle), are_siblings(Parent, Uncle), parent(Parent, Child).
                              
man(jon).

man(stew).
woman(jess).

woman(mum).
parent(mum, jess).
parent(mum, stew).
parent(mum, dan).
parent(mum, dylan).

man(dad).
parent(dad, jess).
parent(dad, stew).
parent(dad, dan).
parent(dad, dyland).

man(grandad).
parent(grandad, dad).
parent(grandad, neil).

woman(grandma).
parent(grandma, dad).
parent(grandma, neil).

man(neil).