The Twins in Brazil

There's a region in Brazil where so many twins have been born — in one village of 350 people, 10 percent of births were of twins — that residents have many theories as to why, from there being something in the water to the machinations of Nazi physician Josef Mengele, who died in Brazil in 1979. According to a New York Times article, researcher Ursula Matte and her team scoured through the region's drinking water to find nothing unusual and, using baptismal certificates, traced the high incidence of twins in the area to before Mengele was in Brazil. Instead, Matte's team says that the mothers, all part of a highly-related, German-speaking population, share a gene that predisposes them to having twins. "We analyzed six genes and found one gene that confirms, in this population, a predisposition to the birth of twins," Matte says. She notes, though, that this gene many not be universal for a predisposition to twins. "If I take twins from New Zealand and test them, it will probably generate a different result," she adds.