It is possible to make this case.
I recall reading(just spent an hour trying to find a link, I could not do it)that Stanley Dunham Sr. cavorted with black whores in Honolulu and its very possible one of them was zeros mother.
Dunham sr. wanted a boy so bad he named Stanley Ann with a boy's name.
This would explain a lot. The Dunhams interest,inheritances,CIA connections, etc. Also would make him a true American citizen.I only wish I could corroborate all this.
I think Stanley Ann is the mother explaining the resemblance to Grandpa.