“CANDIDO GODOI, Brazil – High atop a hill behind his family’s home, Derli Grimm knelt and took a sip from a thin black tube leading from a natural spring.

Like so many in this farming town, populated almost entirely by German-speaking immigrants, Grimm, 19, believes that something in the water — a mysterious mineral, perhaps — is responsible for the town’s unusual concentration of twins.

”It can’t all be explained by genetics,” said Grimm, himself a twin.

Geneticists would like to disagree with him, but even they have no complete explanation for the 38 pairs of twins among about 80 families living within an area of 1.5 square miles.

The mystery has persisted for decades, attracting international attention and inspiring books and investigations by geneticists. It is one reason locals are in no hurry to try to prove their water theory. They are too busy posing for journalists and marketing themselves to tourists as the “twins capital of the world.”

Some researchers have suggested the darker possibility that Josef Mengele, the Nazi physician known as the Angel of Death, was involved. Mengele, locals say, roamed this region of southern Brazil, posing as a veterinarian, in the 1960s, about the time the twins explosion began.”

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