The US Constitution does not specify married US parents.
Actually, I'm not.
If the Kenyan Mau-Mau had been married to a Luo woman back home, then any pretended marriage he had acted out with Stanley Ann Dunham to stand up her no-doubt accidental pregnancy (and foolish, and ....) as somehow righteous, would have been null and void under U.S. law because bigamous.
Which would make Junior a ringtailed bastard and one-parent child. No daddy in the law. Right?
So how would that impact NBC status for him, if there was no father in the picture?
Consider: If Stanley Ann had become pregnant after a happy weekend having sex with eight or ten different guys, there would be no way to tell, without paternity testing (which isn't legally required in such cases), whose spermatocyte won the baby race.
With an Oort cloud of possible daddies available, or none in sight and she ain't talking, then how do you determine NBC status of an illegitimate infant?
That's my point.