Any idea of how one record can use data from on field of another record (from the same table) and add data to it ?

One drawing can be more explicit. I am trying to do this :

To be more specific, I am trying to make the "ancestors filed".

Two records have one child, so the child have two parents. But, since each parents have two parents, the child have four grand parents. And if we keep adding grand-grand-grand... parents, the child will have more and more ancestors.

So I need an "ancestor" field that can keep track of all the ancestors of the child. But I really don't know how. Maybe, it's easy.

Any idea ?

Regards