As ever, this depends on the definition of NBC. So far as I know, the prevailing (not to say correct) interpretation of this is “one who is legally a citizen due to circumstances at / of birth” — that is, someone who has always been a citizen as opposed to someone who BECAME one afterwards through naturalization, act of Congress, etc. Obviously if this interpretation were applied to Ted Cruz, he’s and NBC.
Others believe that the definition should be more narrow and limited to “one born of parents who were US citizens at the time of the birth.” Cruz isn’t an NBC under THIS view.
Not gonna get into that debate again!
There are a number of possibilities here.
Born in US to two citizen parents. NBC by any criteria.
Born in US to one citizen and one non-citizen parent. (BO's situation.)
Born outside the US to two citizen parents.
Born outside the US to one citizen and one non-citizen parent. Some believe father or mother being citizen should make a difference.
Personally, I define NBC as "citizen at birth."
But would take SCOTUS ruling to settle it.