Gibbs has been denying the birthers' claims for weeks now.
At a July 27 press conference, Gibbs dismissed the rumors as "made-up fictional nonsense of whether or not the president was born in this country."
"If I had some DNA, it wouldn't assuage those who don't believe he was born here," said Gibbs, who added that he posted the president's birth certificate online last year.
"The president was born in Honolulu, Hawaii, the 50th state of the greatest country on the face of the earth," he said.
Gibb's said the president's citizenship "has been proven ad nauseam."
As to why the rumors persist, Gibbs said, "because for $15 you can get an Internet address and say whatever you want."