Hi Lisa,
This would be a standard used for many years in research data sets. This Center for Statistical Genetics page has a decent description and example. They write,
"Although pedigrees can become quite complex, all the information that is necessary to reconstruct individual relationships in a pedigree file can be summarized in five items: a family identifier, an individual identifier, a link to each parent (if available) and finally an indicator of each individual’s sex.’’
So if one wanted to represent pedigrees, you would only need to add fields for person_id’s for the father and mother. Why I would argue against a family identifier, is that if one had the full family tree of humanity, everyone is related – the family_id is a holdover from how pedigrees would be collected within large extended families. However, you could imagine problems arising with two “families” overlapping through the relationship structure defined by the relationship links from person_id, father_id, and mother_id, and then two related people could be listed as having different family id’s.
Hope this helps,
Christophe