Yes, but only if they are automatically adquired at birth: * A child born to an American parent and a German parent acquires both American and German citizenship at birth, regardless of place of birth. This doesn't apply to children born in U.S. soil to foreign government officials on assignment to the U.S. * a child born in Germany to two American parents may also become a dual national at birth, only if: - at least one parent had lived legally in Germany for at least eight years prior to the birth - at the time of the birth, that parent had a permanent residence permit - birth date is after February 2, 1990 In the second case, the person has to choose between American and German citizenship before turning 23. An American who becomes a German citizen should formally renounce his/her American citizenship, and also a German who becomes an American citizen must give up his/her German citizenship.