I know many people who have taken advantage of DNA testing to find out information about their ancestry. I have not been tempted to do so because I am not interested in what percentage of my ancestry comes from various parts of the globe. Since I grew up in an island where my known ancestors also lived, I suspect that one would have o go back quite far to find traces of ancestors from other parts of the world. Even then, and even if there are surprises, I am not sure what I would do with that information. But I can understand why it might appeal to some in the US where people come from all over the world and have ancestors who were fairly recent arrivals, say within the last 200 years, and seem to have great curiosity about their ancestry. Thus they might find interesting tidbits.
There are claims that some of these services can also alert you to genetic predispositions to certain diseases.
Knowledge of a person’s ancestry can be important because the frequencies of genetic risk variants sometimes vary with ancestry, although most such risk variants are not assayed directly by ancestry tests. However, some DTC ancestry testing companies provide health reports in which they directly test a limited number of DNA variants associated with conditions such as breast cancer and Alzheimer disease or less common genetic conditions such as cystic fibrosis, polycystic kidney disease, and various inborn errors of metabolism (the latter enabling identification of carrier status).
In most genetic research studies of health and disease, ancestry information has replaced the use of racial categories. Because of its increased accuracy in comparison with self-reported ancestry, genetically estimated ancestry can improve statistical power to detect genetic risk factors for common diseases in genome-wide association studies. Often such risk factors vary by ancestry, and the cumulative disease risk aggregated across multiple DNA variants (ie, the polygenic risk score) appears to be highly sensitive to differences in ancestry. Accordingly, if the clinical utility of polygenic risk scores is eventually established, ancestry information could be important for accurate interpretation of risk. Moreover, because the great majority of genetic studies have been done in populations of European ancestry, the pathogenicity of rare variants is more difficult to assess in persons of predominantly non-European ancestry. Ancestry information can thus help to avoid misinterpretation of genetic tests.
Ancestry testing also can yield unanticipated results such as lack of expected ancestry or the presence of unexpected ancestry. Discordance between pairs of siblings or between father and child can reveal nonpaternity, which is estimated to occur in approximately1% to 2% of births in Western populations. Large identical regions of DNA on both chromosomes in a tested individual can identify parental consanguinity. These results could have significant psychosocial impacts.
As the last paragraph indicates, these services can also throw up surprises, some unpleasant and others awkward, about family relationships. I was reading about a woman who subscribed to such a service and learned that her deceased father (who had been in the US military and had served in many places) had had a child with another woman while being married to her mother. That half-sister now wants to get in touch with her and keeps pestering her to make contact. But this woman does not want to deal with a new family member late in her life. Even if she manages to successfully ghost the new person, the knowledge will still be there and cause her discomfort.
I do not know how these ancestry services work, since I have never used them. But I was surprised that they enable one to actually find out who one’s relatives are, or at least give enough information to enable one to track them down.
Ah, that was in a recent letter to Ask Amy, wasn’t it? I read the advice columns run by the Washington Post and recognized it.
Yes, it was.
I was adopted when I was just three months old. I can’t remember a time when I didn’t know that, so my parents must have told me as soon as I was old enough to understand the concepts. One side effect of that is that I have always thought that my parents were the ones who took care of me when I needed them; and I’ve never had the desire to find out who my sire and dam were. I’d be willing to meet biological relatives if they wanted to meet me; but I don’t feel any need to initiate the process.
For a time a few decades ago, I thought it would be useful to have a medical history; but now that I’m 77, that hardly matters.
“I was surprised that they enable one to actually find out who one’s relatives are, or at least give enough information to enable one to track them down.”
Oh, yes. Nowadays, even if you personally never got genetic analysis, if enough of your relatives did, police can often identify you from a used drink cup or a cigarette butt. The so-called Golden State Killer was found that way.
Oh yes, 23andMe sends me an email almost monthly, excitedly announcing that “You have new DNA relatives!” These are almost always “4th cousins”, i.e. we have a great-great-great-grandparent in common, and thus share about 0.2% (0.002) of our DNA.
One time, though, it was a first cousin (12% shared DNA), unknown to my side of the family, thus exposing a previously unknown incident in the life of a deceased relative.
Such discoveries depend entirely on chance: who opts to sign up for which service (23andMe, Ancestry, etc.) and when. With several million customers for each of those sites — of course, still only around 1-2% of the population of the USA — the odds of surprising discoveries have gotten better.
Aside from genealogical connections, these sites will tell you if you are a carrier for, or predisposed to, any of a long list of genetically-based illnesses. That can be worthwhile.
Speaking of 23andMe, the companys response to a recent data breach that involved millions of records being stolen was to further limit their customers rights under the law:
Data stolen, we’re told, has been confirmed to come from “DNA relatives” profiles that indicate how folks may be related, of which 5.5 million sets of data were stolen. Data swiped in the breach included names, ancestry information, self-reported location, birth year, links to family trees, and anything that may have been included in self-descriptions added to user profiles.
An additional 1.4 million sets of Family Tree data was stolen as well, 23andMe said, which includes similar information as well as relationships to the individuals whose accounts were compromised.
In response, 23andMe seems very concerned at the potential legal ramifications of the breach, and has updated its terms of service in what appears to be an attempt to avoid a wave of lawsuits.
A side-by-side comparison of 23andMe’s new terms of service, dated November 30, and its previous version from October 4 (prior to the breach), teased out a new dispute resolution period of 60 days during which aggrieved customers agree to “first attempt to negotiate any dispute informally … before either party initiates any arbitration or court proceeding.”
https://www.theregister.com/2023/12/11/in_brief_security/
I thought we all shared 99.9% of our DNA…
“nonpaternity, which is estimated to occur in approximately1% to 2% of births in Western populations.”
Estimated by some touchingly naive people with an overdeveloped tendency to believe women.
Actual medical research available online has a lower bound of 1%,it’s true, but the commonly quoted upper bound is TEN per cent, not two. If you’re getting hit up for child support, get a test. Those are bad odds.
xohjoh2n, maybe, but the genome is not small in terms of base pairs, and 0.1% of 6.27E9 is 6.27E6.
cf. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391780/
I hadn’t thought about it before, but this is kinda obvious after the fact:
https://www.abc.net.au/news/2024-01-17/genetic-testing-or-life-insurance-comedian-michelle-brasier/103349872