It's been an inexplicable phenomenon for decades: a remote Brazilian village full of blond-haired, blue-eyed twins. Dozens and dozens of twins, all with the clean-cut Aryan features that Nazi war criminal Josef Mengele wanted in his genetically altered master race.

Could Mengele -- who fled to South America in 1949 -- have had a hand in the bizarre outbreak of Germanic twins in Candido Godoi, Brazil?

That's the puzzle the National Geographic Channel tries to solve in its latest documentary, "Nazi Mystery: Twins from Brazil," which airs tonight at 9 p.m.

The show pits Argentine historian and journalist Jorge Camarasa against Mengele expert Gerald Posner.

Camarasa grabbed headlines around the world when he published a book in January touting his theory that Mengele not only traveled to Candido Godoi in the 1960s, he posed at various times as a vet and a doctor who treated pregnant women.

But Posner, who has examined just about every top-secret document filed by Argentine, Brazilian and Israeli authorities on Mengele, is unequivocally convinced that Mengele never visited the remote village.

Weighing in as a neutral arbiter is a team of geneticists and biologists from Porto Alegre in southern Brazil, who visited Candido Godoi to gather bloodwork from every living mother who has given birth to twins -- a staggering percentage of the tiny town's population.