WASHINGTON – Why do so many Americans still believe Barack Obama was born in Kenya?

Maybe because he keeps insisting it's so.

He did again last week, while visiting his ancestral homeland of Kogelo.

Participating in the opening of Sauti Kuu Resource Center, a youth facility built by his half-sister, Auma Obama, he said: "Now, three years ago, I visited Kenya as the first sitting American president to come from Kenya. When I was president it was a little bit harder to get up here cause my plane didn’t fit the tarmac up here."

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"While three years ago my sister Auma introduced me before I gave a speech, today I'm really coming as a brother, as a citizen of the world, as someone with a connection to Africa to talk about the importance of what she’s doing but also to create a larger context for what’s possible," Obama continued.

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So, which is it – native-born son of Kenya, native-born son of Hawaii or native-born citizen of the world?

As far back as at least 1991, Obama and those around him, have been referring to him as Kenyan-born.

Back then, it was his literary agent, Acton & Dystel, promoting his first book, "Dreams of My Father" that produced a brochure produced that made the claim.

Mistake? That’s what Obama spokesmen said. Yet "Dreams of My Father" didn't actually get released in 1991. It wasn’t released until 2004, but pre-publication publicity at that time were still making the claim – just four years before he ran for president. The bio noting his birth in Kenya was still being circulated three years later in 2007. The birthplace was change in the bio April 21, 2007, less than a year before he would announce his campaign for the presidency.

While allies of the former president have been quick to blame his political enemies for continuing to plant doubt about Obama's constitutional eligibility to occupy the White House, obviously not all the assertions being made come from so-called “birthers,” a term of derision used by his friends and supporters.

In fact, some of his friends and supporters in Kenya still insist he was born there.

Even Michelle Obama referred to Kenya as "his home country."