Well . . .  seems like a natural reaction based on his early years ; a deep bow sure is a dead giveaway..
(c) Obama's Kenyan birth father: In Islam, religion passes from the father to the child. Barack Hussein Obama, Sr. (1936–1982) was raised a Muslim and named his boy Barack Hussein Obama, Jr. Only Muslim children are named "Hussein"(c)

(c)Obama's Indonesian family: His stepfather, Lolo Soetoro, was also a Muslim. In fact, as Obama's half-sister, Maya Soetoro-Ng explained to Jodi Kantor of the New York Times: "My whole family was Muslim, and most of the people I knew were Muslim." An Indonesian publication, the Banjarmasin Post reports a former classmate, Rony Amir, recalling that "All the relatives of Barry's father were very devout Muslims"(c)

(c) "In his autobiography, Dreams of My Father, Obama relates how he got into trouble because he "made faces during Koranic studies," thereby revealing he was a Muslim... 

http://www.danielpipes.org/5544/barack-obamas-muslim-childhood

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