Yeah, that’s basically a graph problem. Map each person to a node, each parent-child link to an edge, then run a search to see if two nodes share a close ancestor. I can script that in a few lines; just let me know the data format.

IDs should be plain ints or UUIDs; just keep a single source of truth so you don’t end up with duplicate IDs for the same person. For cousin levels, build a helper that walks up the ancestor tree and records depth; two people are n‑th cousins if their lowest common ancestor is n+1 generations back for each of them. Then flag any that fall below your forbidden threshold. Python’s dicts and recursion will do the trick—no need for a full library.