There was an interesting article in the journal Science a few years ago in which more than a dozen scientists and researchers from various backgrounds expressed analysis of genetic tests and the limitations of these tests. The conclusion was that these vanity tests have significant scientific limitations and rely heavily on misconceptions about race and genetics.
More people took genetic ancestry tests last year than in all previous years combined. The number of people who have had their DNA analyzed with direct-to-consumer genetic genealogy tests more than doubled during 2017 and now exceeds 12 million, according to industry estimates. ~ Massachusets Institute of Technology
In the six years before 2017, only 460,000 people purchased genetic ancestry tests, according to a recent study. That trend is likely to increase, scientists say, fueled by hyped promises from companies selling the tests and by news stories about test-takers such as Oprah Winfrey learning she is Zulu or a Floridian accountant being told he descended from the Mongolian warlord Genghis Khan.
But such results are beyond the capabilities of current tests, scientists say. In the Genghis Khan example, the company that performed the test, Oxford Genetics, did not have DNA samples from the Mongol warlord himself because his tomb has never been found.
Instead, the company found that the accountant had a set of genetic markers very common in people from Eurasia, and particularly in the areas where Genghis Khan conquered. The rest was inference. There's nothing to tie the accountant to Genghis Khan. It could have been some other guy alive at the time of Genghis Khan who slept around a lot.
As for Oprah, she only had a trace of Zulu DNA, which does not make her Zulu.
There are several companies now claim that for as little as $60 and a swab of the inner cheek, they can reveal a person's family tree and ancestral homeland. However, the establishment of rules and guidelines for genetic testing has only recently begun; its legislation around the globe is weak, and many claims that are not backed by any valid scientific reasoning. At the same time, human geneticists are learning that the analysis of complex risk factors and susceptibility genes is much more difficult than expected.
More than a dozen scientists from various backgrounds now say such "recreational genetics" or "vanity tests" have significant scientific limitations and rely on misconceptions about race and genetics.
If a test-taker is just interested in finding out where there are some people in the world that share the same DNA as them, then these tests can certainly tell them that. But they're not going to tell you every place or every group in the world where people share your DNA. Nor will they necessarily be able to tell you exactly where your ancestors lived or what race or social group they identified with. ~Deborah Bolnick of the University of Texas in Austin.
Most genetic ancestry tests involve the analysis of small snippets of DNA passed down only through the mother, or only through the father. These tests can identify related individuals who share a common maternal or paternal ancestor, and even where in the world people with your genetic signature live today.
A common misconception about genetic ancestry testing is that it can reveal information about an individual's ancestry. It cannot.
One of the more popular tests is offered by the Web site Ancestry.com that allows people to mail in DNA samples to see if they have "genetic cousins" in the company's database and reveal their ancient origins.
One problem with this approach, scientists say, is that because such tests analyze less than 1 percent of a person's genome, they will miss most of a person's relatives.
People assume these tests can tell you your race or ethnicity and reveal exactly where your ancestors lived or exactly what social group they identified with. If you take a mitochondrial DNA test, you learn something about your mother's mother's mother's lineage. If you go back 10 generations, that's telling you something about only one out of more than a thousand ancestors. ~Deborah Bolnick of the University of Texas in Austin.
Such tests also cannot account for recent migrations of peoples from their ancient homelands. Present-day patterns of residence are rarely identical to what existed in the past, and social groups have changed over time, in name and composition.
Bolnick and her colleagues encourage professional genetic and anthropological associations to issue policy statements about genetic ancestry testing that urge either caution on the part of consumers or set limits on the claims companies can make.
Bolnick stated that she would like to see some independent source of information about these tests so consumers could go somewhere besides the companies themselves and get information about what the test can and cannot tell them.
The Good of DNA
While the testing may not be able to prove your actual ancestry, they can often help you find relatives, especially in the USA. As most of those tested are in the USA, this suggests that around 1 in 25 American adults now have access to personal genetic data—a figure that could spur a range of new genetic analysis services.
The boom comes amid a price war in which companies offered under-$60 tests and 2-for-1 deals during an end-of-year blitz of advertising and discounts.
As for finding relatives, as the FBI and other law enforcement officials found out earlier this year just how easy it could happen. Until recently DNA tests were something the FBI used to find criminals, or they were used to identify the remains of individuals who could not otherwise be identified. However, unless the individual's DNA were in their database, they would never have found the individual.
Now, with millions submitting their DNA to online websites, the online DNA database assisted law enforcement in finding one such individual.
From 1974 to 1986, the Golden State Killer terrorized the areas of Contra Costa County, Modesto, Sacramento, and Stockton, California. He was a serial killer of 13 individuals, more than 50 rapes of women and girls ages 13 to 41, and over 100 burglaries during the time. He was believed to be responsible for three crime sprees throughout California, each of which spawned a different nickname in the press before it became evident that they were committed by the same person.
During the investigation, several suspects were cleared through DNA evidence that had been collected at the scenes. The hunt for the Golden State Killer was a factor in the establishment of California's DNA database, which collects DNA from all accused and convicted felons in California and has been called second only to FBI database in effectiveness in solving cold cases.
The FBI and local law-enforcement agencies decided to send a sample of the killer's DNA off to the web-based DNA testing site. The information about possible relatives that was returned allowed them to look for a relative within the group that fit the age, description and who had lived in the area of California from 1974 to 1986. This limited it to just two males. After following them and collecting residual DNA from their used coffee cups and a car door handle, they found their man.
On April 24, 2018, authorities charged 72-year-old U.S. Navy veteran and former police officer Joseph James DeAngelo with eight counts of first-degree murder, based upon DNA evidence.