PHILADELPHIA — It's the ultimate rabbit hole of hobbies: genetic genealogy.
There are legions of self-taught ancestry bloodhounds who upload their DNA to multiple databases in search of kin who did likewise, plugging gaps in their family tree.
Joseph Augustus Zarelli's biological mother had third and fourth cousins who did just that. They had uploaded their DNA to GEDmatch — a database that law enforcement and forensic scientists can access to help solve cold cases.