Mousing over family member names on a profile or edit page provides self-evident pieces of data like "father", "brother". There's an opportunity to do something very useful and that's to provide the birthdate (in brief canonical form), the first 15 characters, say, of birthplace, deathdate in brief, and deathplace. Or maybe birth, death and spouse name would be better, saving a click to get that information.
This costs nothing in compute time until it is asked for.