The Central African country of Benin produced the highest rate of twin: 27.9/1,000. While all of Central Africa has a higher than average twin rate (18/1,000), Benin reported even more twins! Like Nigeria, long recognized as a hotbed of twinning, Benin is home to many families from the Yoruba tribe. Some attribute their abundance of twins to diet; the Cassava, a type of yam, may induce hyperovulation.
My Great Source of Info. - About.com http://multiples.about.com/b/2011/10/17/who-has-the-most-twins.htm
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