Photos from Taryn Simon's work that investigates 18 family bloodlines. Photo by Taryn Simon For China Daily

"But even that rigor couldn't prevent the inevitable disruption. I would show up and suddenly someone mentions a brother that had never been previously discussed with me," she says.

When they traveled with a ton of gear to accommodate their moving studio to Tanzania to photograph the bloodline of the director of the Tanzania Albino Society, their equipment was seized by corrupt authorities and $80,000 was demanded for its return.

"Albinos in Tanzania are hunted by human poachers who trade their skin, limbs and organs for large sums of money to witch doctors who promote the belief that albinos have magical powers. This is a subject the authorities are not keen to publicize," she says.

For the people she wants to photograph, there was typically an understanding and desire to participate. But for those who didn't show up because of reasons ranging from imprisonment, military service, women not granted permission to be photographed for religious and social reasons or individuals who didn't want to be associated with the story, she uses empty portraits.

She has published her photography since 2003, with The Innocents, documenting stories of people who served time in prison for violent crimes they didn't commit.

In 2007,she confronted the divide between public and expert access through An American Index of the Hidden and Unfamiliar, to see how far she could get as an individual citizen, or outsider.