George Washington's adopted son was a bit of a ne'er-do-well by most accounts, including those of Washington himself, who wrote about his frustrations with the boy they called "Wash." ...

The research team used Y chromosome DNA to study the paternal relationships in the Washington family tree. A new method of sequencing genetic data allowed the team to study nearly 100,000 single ...

They attributed this to pedigree collapse — when marriages between relatives shortens the number of ancestors — caused by multiple cross-cousin marriages in the Washington family tree. “The ...