recursion - Prolog- family tree of children -

if wanted recursively go down family tree in prolog , return children of every branch, how start that?

thanks

assume following tree, children in red

a simple solution be:

male(lennart). male(mike). male(donald). male(usain). male(joar). male(adam). male(dan). male(simon). female(hillary). female(elise). female(lisa). female(lena).  parent(mike, lennart). parent(mike, lena). parent(lennart, donald). parent(lennart, hillary). parent(lennart, usain). parent(lena, adam). parent(lena, simon). parent(adam, dan). parent(donald, lisa). parent(hillary, joar). parent(hillary, elise).   child(lisa). child(joar). child(elise). child(dan). child(simon).  %% predicate rules father(x,y) :- male(x),parent(x,y). mother(x,y) :- female(x),parent(x,y). son(x,y) :- male(x),parent(y,x). daughter(x,y) :- female(x),parent(y,x).  family_children(x, x):-     child(x).  family_children(x, child):-     parent(x,y),     family_children(y, child). 

test run:

[debug]  ?- family_children(mike, child). child = lisa ; child = joar ; child = elise ; child = dan ; child = simon ; false. 

this quick example of how done, example relies in assumption child cannot have child, solution improved , can add rules cousin/2, grandfather/2, sister/2, uncle/2 etc...

hope got hang of idea now, luck.