We are becoming accustomed to hearing about genealogical discoveries made through the miracles of DNA analysis. But a recent genealogical breakthrough was made by a much older means--noticing a family dental trait.
In 1832, fifty seven recent Irish immigrants died while working on a track of railroad, known as Duffy's Cut, outside of Philadelphia. An excavation of the bodies is ongoing. Recent discoveries have revealed that some of the men did not die of cholera, but of blows to the head. Others may have been shot. An excellent article by Lori Lander Murphy, describing the history and discoveries at Duffy's cut, can be found via the link below.
One skull was found to have a missing front molar (from birth). Members of the Ruddy family in Co. Donegal, hearing about the research being done in Pennsylvania, alerted the researchers that many members of their family has a genetic quirk--a missing front molar! So, the body of young John Ruddy was the first to be identified and matched with his Irish family.