I need some #lisp help.

I'm stuck on a recursion exercise - have been for 2 days!

We're given a at a structure a list of lists, where each such list is of the form (person mother father) .. and so a lot of these together create a family tree.

I want to write a function lineage x y which returns a list of ancestors from x to y ... eg x, mother of x, father of prev, y .... or NIL if y is not an ancestor of x.

I found this easy in #prolog (I wrote this https://prologbyexample.blogspot.com/2023/02/introducing-recursion.html ) but not #lisp.