The instance of twins is about 2.3% worldwide (1.2% in Western Europe, and 8% in Japan). In Nigeria, the rate more than doubles to five sets of twins for every hundred births. In Igbo-Orba, a small, rural community, the Yoruba people are very proud of their twins. The 71 year-old community leader, Olayide Akinyemi boasts, “there is hardly a family here without a set of twins.” He has had three sets with his wife, and his grandparents had ten sets.
Scientists are unsure why this happens with such frequency. Some believe that yams, one of Igbo-Orba staple foods, are high in phytoestrogens; and, that women who eat a lot of them may have increased egg production, causing more cases of fraternal twins. There is no current medical study that connects the eating of yams with higher rates of twins, however. Others believe that it is a simple matter of genetics: families with a history of twins are more likely to have twins in the future; so, when families with twins from all over Nigeria came to Igbo-Orba to avoid the pre-colonial practice of killing twins, and sometimes their mother, at birth, it increased the overall instance of twins in the community.
Whatever the reason, the Yoruba people treat their twins with love and respect, but also believe that twins have divine powers. In Igbo-Orba, it is believed that twins share one single soul, so if one of them dies in childbirth or later in life, the remaining half of a soul will live in an Ibeji. This small wooden figure is clothed, fed, and cared for like a real baby. The Ibeji will carry the half-soul for the rest of the remaining twin’s life, and it is used as a tool to help the mother cope with the tragic loss of a child. She will be responsible for its care and welfare until the living twin, the other half of its soul, is old enough to take over the responsibility.