Good thing he had no natural descendants.
I did not know that but true.
But he did adopt Martha's children by her first husband, John and Martha. John however, as a Colonel in the Continental Army, died of "camp fever" just before the Victory at Yorktown. However G. Washington then adopted John's two younger children, John and Elanor Custis If that was a "legal" adoption, allowing them to inherit, then they, and their decendants, inherited the debt as well. In fact other than Mt. Vernon, that's probably about all they inherited anyway.
In verifying that, I came accross The Death of George Washington, by his grandson John, then 19. Have your hanky ready.