This is actually an interesting point. Barack Sr. was already lawfully married to another woman, as I recall.
http://www.washingtonpost.com/opinions/obama-and-romney-both-come-from-a-ancestry-of-polygamy/2012/04/12/gIQA3TI8CT_story.html
Yep. Stanley Ann wasn’t aware of this, but it seems to have been true.