Trees can't be used for relationships, due to the crazy things that people can do with each other. You'll need a DAG, and you'll need to detect cycles. https:

Trees can't be used for relationships, due to the crazy things that people can do with each other. You'll need a DAG, and you'll need to detect cycles. https://stackoverflow.com/questions/6163683/cycles-in-family-tree-software https://stackoverflow.com/questions/6163683/cycles-in-family...