You haven’t addressed the biographies. The simplest explanation is that Obama himself claimed to be born in Kenya. It’s high time for a hard look at Obama’s history.
More than a year before the publisher’s promotional bio for Obama’s never published book was written there were articles in major newspapers about Obama becoming the first black editor of the Harvard Law Review. Those articles which were written in advance of the “born in Kenya” error named Hawaii as Obama’s birthplace.
Here’s a link to the February 6, 1990 New York Times article:
http://www.nytimes.com/1990/02/06/us/first-black-elected-to-head-harvard-s-law-review.html
And the March 20, 1990. Los Angeles Times article which also names Hawaii as Obama’s birthplace.
http://latimesblogs.latimes.com/thedailymirror/2008/09/barack-obama-ha.html
There were also articles in the Washington Post and the Chicago Tribune which also say “Hawaii.”
The woman who actually wrote the 1991 promotional bio (Miriam Goederich) has said that it was her mistake. I have no reason to doubt her.