Checkout datomic, you can query for facts given a certain point in time. This is common among customer preference storage too, like, "what's your favorite song or movie can change easily over time." Being able to query the state at a certain date can be helpful. Some predictive analytics can also be done like people with these preferences, how did they change once they had a family, or moved to another "life stage".

Though you probably don't need datomic, it would be not too complicated to model this in neo4j or some other RDF graph that supports arbitrary sized tuples. Datomic just supports this feature as a first class value offering.