The immigration law of 1952--in force at the time of Obama's birth stated that a child born to a US citizen mother in the US, was always a citizen at birth. But if born in another country, the mother would have had to reside in the US for at least 5 years from her 14th birthday. On August 4, 1961, Stanley Ann Dunham (born in 1942) was 18. She would not be eligible to pass on citizenship until November 29--her 19th birthday.
Also, lj, your "Frenchie" was Swiss.