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				Sights like this can be seen everywhere in Igbo Ora, where a 
				banner welcomes visitors to the "twins capital of the world".
 Twins are common in the Yoruba ethnic group that dominates this 
				part of Nigeria. A 1970s study by a British gynecologist found 
				that around 50 sets of twins were born out of every 1,000 births 
				in the southwest - one of the highest rates of twin births in 
				the world.
 
 In Yoruba culture twins are so common that they are 
				traditionally given specific names. They are called either Taiwo 
				or Kehinde depending on whether they were born first or second.
 
 But even for Yoruba people, Igbo Ora is considered to be 
				exceptional. Among the nearly 100 secondary school children 
				assembled at the end of their break there were nine sets of 
				twins.
 
 "There are so many twins because of the okra leaf that we eat," 
				said 15-year-old Kehinde Oyedepo, one of the twins, repeating a 
				view commonly held in the town.
 
 The leaves are used to make a stew that is popular in Igbo Ora.
 
 Others have pointed to the popularity of Amala - a local dish 
				made from yams and cassava flour. One theory is that yams prompt 
				the production of gonadotropins, a chemical agent that 
				stimulates the production of eggs.
 
 Ekujumi Olarenwaju, an obstetrician gynecologist based in Lagos, 
				around 100 miles (160 km) away, believes the causes of the 
				phenomenon lie elsewhere because the same kind of yam is eaten 
				elsewhere in the world without the same result.
 
 "Thus far scientifically, no one can say this is the reason," 
				said Olarenwaju. "One of the plausible reasons is the hereditary 
				aspect of it because maybe over the years they inter-marry, they 
				now have that gene being pooled and concentrated in that 
				environment," he said.
 
 But the women who sell piles of okra leaves at a town market are 
				quick to disagree.
 
 They said local traditions over how the leaves are consumed were 
				crucial. For example, a stew made from the leaves should be 
				eaten immediately and never stored.
 
 Oyenike Bamimore, who sells the bread, said she was living proof 
				that the diet was the cause. "Because I eat okra leaves a lot, I 
				gave birth to eight sets of twins," she said.
 
 (Reporting by Alexis Akwagyiram; Additional reporting by Seun 
				Sanni, Afolabi Sotunde and Angela Ukomadu; Editing by Giles 
				Elgood)
 
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