http://www.scribd.com/doc/29342223/Morse-Natural-Born-Citizen-1904
Our conclusion is that the child of citizens of the United States, wherever born, is “a natural-born citizen of the United States,” within the constitutional requirement; and, as such, if possessed of the other qualifications, would be eligible for the office of president of the United States.
Cruz was the child of one US citizen and one foreigner.