genealogists have determined that which u.s. president was related to eleven other presidents?

Franklin Delano Roosevelt is the U.S. president whom genealogists have determined is related to eleven other presidents.

He is documented as being distantly connected—some by blood, some by marriage—to presidents including John Adams, John Quincy Adams, Ulysses S. Grant, William Henry Harrison, Benjamin Harrison, James Madison, Theodore Roosevelt, William Taft, Zachary Taylor, Martin Van Buren, and George Washington.