As more Americans take advantage of genetic testing to pinpoint the makeup of their DNA, the technology is coming head to head with the country’s deep-rooted obsession with race and racial myths. This is perhaps no more true than for the growing number of self-identified European Americans who learn they are actually part African.

For those who are surprised by their genetic heritage, the new information can often set into motion a complicated recalibration of how they view their identity.

Nicole Persley, who grew up in Nokesville, Va., was stunned to learn that she is part African. Her youth could not have been whiter. In the 1970s and ’80s in her rural home town, she went to school with farmers’ kids who listened to country music and sometimes made racist jokes. She was, as she recalls, “basically raised a Southern white girl.”