In addition Obama’s father was a foreign national (never even and immigrant to this country) in a 2nd marriage bigamous marriage with Obama’s teenage mother who per U.S. law back then did not allow for a teenage mother married to a foreign national to pass her U.S. citizenship to her children. She was only 18 and per the controlling law back then she would had to be 19 to pass on her U.S. citizenship to Obama. Thus Obama’s claim at birth to even being a U.S. Citizen at all (let alone not being a “natural born Citizen” is very tenuous, to say the least. And if proven he was not born in the USA as many believe, then Obama was never even a U.S. Citizen at birth at all. See more evidence about Obama the fraud here: https://www.scribd.com/user/52640192/protectourliberty/lists
If Obama was born in the US and his mother was American and his father wasn’t a foreign diplomat, Obama would indeed be a US citizen by birth. If his parents’ marriage was invalid, then Obama would have inherited his mother’s American citizenship. See the interesting case of Australia’s current PM who got around a real ban on foreigners’ children serving in Parliament by claiming that his parents weren’t married and that no father’s name appeared on his birth certificate.