Mike Zullo has said in interviews that there is no definitive proof Stanley Ann Dunham was his real birth mother.
If BHO's birth mother is not Stanley Ann, could he have been born in Connecticut and been adopted by Stanley Ann? Maybe his birth mother gave him up for adoption because he was a mixed race baby and family and friends and community frowned on such.
I believe he has a SSN with a Connecticut SSN. Something like "C" or "Connecticut" have numbers identifying the state by the first time a SSN was needed or requested.