ICYMI: White? Black? A Murky Distinction Grows Still Murkier – NYTimes.com

While not based on a random sample, nevertheless interesting results, showing just how much mixing has occurred, and continues to occur, in the US:

In the United States, there is a long tradition of trying to draw sharp lines between ethnic groups, but our ancestry is a fluid and complex matter. In recent years geneticists have been uncovering new evidence about our shared heritage, and last week a team of scientists published the biggest genetic profile of the United States to date, based on a study of 160,000 people

The researchers were able to trace variations in our genetic makeup from state to state, creating for the first time a sort of ancestry map.

“We use these terms — white, black, Indian, Latino — and they don’t really mean what we think they mean,” said Claudio Saunt, a historian at the University of Georgia who was not involved in the study.

The data for the new study were collected by 23andMe, the consumer DNA-testing company. When customers have their genes analyzed, the company asks them if they’d like to make their results available for study by staff scientists.

Over time the company has built a database that not only includes DNA, but also such details as a participant’s birthplace and the ethnic group with which he or she identifies. (23andMe strips the data of any information that might breach the privacy of participants.)

The scientists also have been developing software that learns to recognize the origins of the short segments of DNA that make up our genomes. Recently they used their program to calculate what percentage of each subject’s genomes was inherited from European, African or Native American forebears.

“This year we saw that we were in a great position to do the analysis,” said Joanna L. Mountain, senior director of research at 23andMe.

On average, the scientists found, people who identified as African-American had genes that were only 73.2 percent African. European genes accounted for 24 percent of their DNA, while .8 percent came from Native Americans.

White? Black? A Murky Distinction Grows Still Murkier – NYTimes.com.