Obama Sr. may have paid Obama’s mother to marry him so as to get a green card.
Sounds like a possible win-win, if the possibility that the Durham family left Washington as soon as their daughter discovered she was pregnant and moved to Hawaii were also true. She’d get a legal father whose lack of presence was understandable (he moved back to Africa, couldn’t stay in the country), her half-black child would be the legal progeny of an intelligent foreign student and not a black dude she did, and he’d get a green card without much work. If all else failed, annul the marriage because of his prior wife/wives.
She may have needed a black daddy for her unborn baby and he needed some help with the visa.