Helpful information about DNA TestingDNA 101: What Is DNA?

DNA stands for deoxyribonucleic acid, the name of a chemical chain that carries the genetic information of our parents and their parents, and so on. It contains the information needed to build different types of proteins that control different things in the body.

DNA is extremely complex.The rungs on the chemical chainstructured as a double helixare called base pairs, and theres over 3 billion of them across the 23 chromosome pairs in the nucleus of each cell in the human body (for a total of 6 billion over the 46 chromosomes). These base pairs make up about 20,000-25,000 genes, which instruct cells on how to build at least 90,000 proteins throughout all 30 trillion cells in the human body.

A single chromosome, therefore, contains hundreds to thousands of genes. A single gene can have anything from 27,000 to 2 million base pairs.

Chromosomes come in two types of pairs: autosomes, which are identical, as found in chromosomes 1-22), and allosomes, which can be different (as found in the 23rd pair). Allosomes determinethe organisms sex (everyone has one pair of these, either YX for males or XX for females).

DNA that comes from chromosomes is found in the nucleus of every cell, but this isnt the only type of DNA direct-to-consumer companies can use to identify ancestry. The mitochondria in cells also carry DNA. Unlike most nuclear DNA, mtDNA is passed practically unchanged from mother to child.

A common misconception is that DNA is like a blueprint for a human body. Instead, DNA chains are a coded list that instructs cells on how to build proteins. One of our interviewees, Professor Simon Fisher from the Max Planck Institutes Department Language and Genetics, sent us this handy explanation.

The human genomethe complete set of nuclear DNAis 99.9 percent identical for all humans. Its the 0.1 percentthat contains enough differences to make us into unique individuals. Understanding how information is passed on through genes, how genes instruct proteins, and how proteins translate into specific processes in the human body, can help us know ourselves better.

Scientists have identified that certain proteins are linked to specific conditions, diseases, or health risks. Certain proteins, for example, are responsible for the production of thehormone insulin. Mutations, changes, and variations in the genes that instruct cells to build this protein can cause a variety of disorders.

Different direct-to-consumer DNA companies have developed algorithms based on these variations. None of them analyze a persons entire, complex genome. Instead, they focus on markers or locations on the gene code that have been associated with certain populations or conditions.

Most commercial DNA kits offer two kinds of tests: ancestry and health.

Analyzing DNA is not as easy as reading a history book. Its not even as easy as reading science-heavy articles about the chemical composition of DNA.

In order to determine a persons ancestry, companies offer different types of tests:

Autosomal tests: these tests focus on autosomes 1-22 plus the X chromosome.

Y-DNA tests: these tests focus on the Y chromosome (if male), which is used to trace patrilineal ancestors because its passed practically unchanged from fathers to sons.

mtDNA tests: these tests focus on mitochondrial DNA, which is used to trace matrilineal ancestors because its passed practically unchanged from mothers to their children.

The autosomal DNA passed on by our parents is a mix of their DNA, and their parents DNA, and so on. The amount of ancestors doubles with each previous generation. That means DNA from only the last two hundred years can already be a mixture of 510 people (less if ancestors appear multiple times in a family tree).

Most ancestry testing, however, compares specific DNA markers (alleles) against those of existing, contemporary populations determined to have remained, historically, in the same place for a long time (each companys reference panel). A company like Ancestry, for instance, uses algorithms to find which ethnicity assignments return the highest probability matches.

This statistical matching, however, is limited by the natural genetic mixing that has historically occurred throughout many populations. Europeans, for example, are historically comprised of mixtures of populations from the region now known as Turkey, the ancient Roman Empire, and Northern Africa. Within the last 2,000 years, Britain alone has experienced immigration and genetic mixing from the Romans, various Germanic tribes, and the Middle East.

In a 2015 article, Jonathan Kahn, a law professor at Northeastern University who has written extensively on genomics and race, writesThe estimates provided by diverse commercial enterprises [...] are premised on a notion of static populations that have not migrated or mixed over time. [...But] the idea that there are somehow pure types of African, European, or Asian DNA is a ction [...]

This article in the American Journal of Human Genetics echoes that--[O]nly a small fraction of ancestors are represented by each given genomic segment in an individual, [...] so one can only ever have limited information on the origins of a given individual's ancestors. This is why some experts, like Professor Troy Duster from UC Berkeley, question the usage of admixture percentages, "Heres the problem in a nutshell. In order to have something called 'percent admixture'percent white, percent black, percent whatever, percent Italian, percent Jewishyoud have to have something called one hundred percent.

Direct-to-home DNA testing companies often use the term ethnicity when providing reports and statistical probability breakdowns for ancestry, health, and traits. Their usage of the term, however, varies, and it is often left undefined. AncestryDNAs White Paper, for example, does not define ethnicity in its glossary, but in its usage throughout, the term is synonymous with regions, populations, or even nationalities.

However, some have questioned the wisdom and utility of the term ethnicitya socially constructed concept based on self-identificationwhen discussing a biological component, DNA, especially in health contexts. Part of the difficulty arises from the often-contradictory nature of available definitions and its overlap with other socially-constructed and controversial terms like race.

This is further complicated by the facts that 1. there are no clear-cut ethnicities because most populations in the world are mixed to some degree, 2. socially constructed concepts like ethnicity and race have, historically, resulted in bias and discrimination, and 3. an overlap between modern ethnicity labels might not correspond to historical population names or locations.

DNA can certainly reveal a lot of information about where our genes come from. However, its important to understand that companies are only providing estimates based on DNA similarities to other contemporary populations. When an ancestry report says a person is 2% Scandinavian, it does not mean a specific, unique chunk of their DNA can come only from Scandinavia. Instead, what this percentage means is that certain portions of their genes have been statistically similar to those from contemporary Scandinavian populations.

This is why an individual can take multiple DNA tests from different companies or multiple tests with the same company, and get different results, and why identical twins have also been documented as having received slightly different reports.

The size of the databases also has to be taken into account. As Scientific American explains, several companies use both preexisting datasets as well as some reference populations that they have recruited themselves. ScienceNews.org cites anthropological geneticist Deborah Bolnick, saying, Who the companies say you aredependsin large parton those reference populations, Bolnick says. For instance, you may carry a pattern of SNPs found in people in both southern France and in Italy. If, by chance, the French people a company sampled had that SNP pattern but none of the Italians in the companys database did, they may infer that you have French ancestors and not Italian because of who they do and do not have in their database.

The Genetic Resource Center for the National Congress of American Indians explains the limitations of making probability estimates based on database comparison and the problem of using this to identify certain ethnic groups. [T]hese results are limited by the information in current databases, many of which do not contain a lot of information for particular groups (AI/ANs among them). This limitation in the data can produce problems for tribes and individuals seeking information as results may not be accurate or even possible to generate given limited availability of comparative data.

Companies like HomeDNA and African Ancestry are currently trying to address some of these limitations for African and Asian populations. As ScienceNews.org comments, some groups, including aboriginal populations in Australia and big parts of Africa and Asia, are mostly absent from companies databases.

Y-DNA and mtDNA are currently the most authentic and useful tests for ancestry, according to Dr. Troy Duster, professor of sociology at UC Berkeley. They are, as he told us, definitive and replicable. However, research suggests that lineage-based genetic estimates [...] reflect only a fraction of any person's total genetic ancestry.

Y-DNA tests can only trace one patrilineal ancestor at each generation because only one ancestor (a father) passed the Y chromosome to the next (his son). That means that, increasingly, at each further past generation, an individual has more and more ancestors that contributed to their genetic makeup, but which can't be reliably identified by tracing their genes.

Mitochondrial DNA tests are similarly limited; only the mothers mothers mothers mothers (etc.) mitochondrial DNA was passed on, meaning only one line can be traced. The paternal grandmothers line for any individual cannot be traced.

Like with ancestry testing, interpreting DNA in order to understand an individuals health risks, is a complicated business. Amy Sturm, president of the National Society of Genetic Counselors, explained how genetic analysis takes place."There is a reference for the normal human DNA code and, based on research that has been done looking at people with certain traits or conditions or diseases, we know that there are certain genes, that if they have a change in them a genetic variant that it would be associated with a certain trait or condition or disease. And so, with the DNA being analyzed in the laboratory, the scientists are looking for changes in the normal DNA code that they know is associated with a trait or condition."

She warns, however, that its usually not a simple 1-1 correlation because there are other genetic factors and environmental factors that likely play a role in that complexity, and we dont have all of those even have those figured out yet. Thus, whether a person takes a direct-to-consumer DNA test or a full test with a genetic counselor, its important they understand that it is more of a risk conversation.

The American Journal of Human Genetics highlights that the scientific claims of companies that choose not to disclose the contents of their proprietary databases cannot be assessed; therefore, the reliability of the information they provide to consumers cannot be verified. This is problematic because, as professor Duster told us in our interview, replicability is the key element in scientific study. However, some direct-to-consumer DNA testing companies are not opening this up to investigation by other scientists saying ok, you can come in and look at our data and see if you can do a replication study.

Ruth Saunders, a law graduate from Queen Mary University of London, echoes Dusters concerns in her 2010 article on the legal implications of DTC genetic testing and the lack of regulatory agencies enforcing scientific validity:The lack of regulation governing the quality of the genetic testing services is a serious concern because a genetic test is only useful to health when its analytical and clinical validity and clinical utility is assured.

Moreover, consumers should be aware that false-positive results can and do occur.

Commercial DNA testing companies often promote themselves through commercials that feature customers with uplifting stories and extremely happy results. Unexpected positive results are certainly one of the biggest draws of this industry, but its important to remember that they are not necessarily the norm.

One common thread across all of our interviewees was that it took a while for the interesting results to come up.

[At first], we just had the estimate genetics. And it was just like that for a while. And every once in a while, somebody would pop up, and it was a cousin that everybody knew, said Erin Dull, who found her half-sister through AncestryDNA.

Adam Lind, one of our employees, similarly described his own experience with AncestryDNA:

I got my results back at the beginning of March 2018. And at first, I was like, 0 for 1 there was no Native American, which is what I wanted to know. But there was a lot of UK DNA, like Irish and I didnt know that the Irish, specifically but there was English, Scottish, and some Western European. And I knew that I had a grandfather from Belgium. So, everything seemed copacetic.

Amy Sturm, president of the NSGC, gave us the following advice regarding managing expectations:

"There are many things people need to think about. You might learn something that youre not prepared to learn. You need to be prepared for this going in. You need to think through for yourself Am I the type of person that would prefer ignorance is bliss? Do I really not want to have family secrets unraveled or unveiled to me? And if so, you might not want to take one of these tests. It depends on the person. Its just something you really have to think about before you spit in that tube."

We spoke to three people who discovered that they had a half-sister, that their father was not their biological father, and that they were at risk of developing breast cancer. These are life-altering scenarios. That said, all three of our interviewees were happy to be aware of these truths about their DNA.

Erin Dull, who discovered her half-sister through AncestryDNA, told us: My life changed. Its the best thing that ever happened to me. Meeting my niece and nephew and having a sister is the greatest thing that ever happened to me.

Similarly, our colleague Adam describes his experience of finding his biological father positively: Hes as excited to know me as I am him. Theres this feeling of make up for the lost time. Im absolutely elated.

Our colleague Sara Altchule, who tested positive for the BRCA 2 gene mutation associated with breast cancer, said to us that, although it was a traumatic experience, she considered it to be the best decision I could have ever made. She documented her experience over several blog posts here.

Although we interviewed three people who experienced amazing or life-changing results, ranging from discovering close family members to a high predisposition towards conditions, this is not necessarily the common outcome. For example, another one of our employees who used 23&Me also commented that hed yet to receive any surprising or unexpected results despite having used the service several months ago.

Two common thread we found through our interviews were either the dont open that can of worms warning, or the if the connection is beyond 1st counsin, Im not interested admission. For example, Erin, one of our interviewees, told us of a friend who had used Ancestry to find her dad. Although he was glad to connect with her, some in the extended family were not, essentially saying we dont know you; youre not a part of this family; we dont want to talk about it.

Theres only one member of the family whos interested; the rest dont even want to talk about it. [One even warned] not to open that can of worms.

This warning is often associated with the potential discovery of family secrets or information that can create an "epistemological crisis,"as professor Duster put it. Not all biological parents want to be found, explores this article on the identity impact these tests can have and many are wary of. Indeed, Ancestrys support center has threads on managing surprising family members and regretting using the service.

On the other hand, some matched family might not want to reply or form a relationship because the connection is vague to them. Adam described his own experience:

The only reason I reached out was because it said father. I think, anything above 'first cousin,' and I would eventually reach out, but other than that, Im not interested. Like, someone who has an ancestor that neither of us has ever met? Im not interested. If someone reached out to me, I would email them back, but I had no interest in reaching out to anybody.

Personal identity is a complex concept influenced by many different factors. But concerns have been raised by experts in bioethics, sociology, anthropology, and genetics about the marketing claims of some DNA testing companies. Some ads for testing companies reinforce the link between DNA and identity, writes ScienceNews.org. For example, AncestryDNAs main page claims You could be Irish; 23&Me promises theyll help customers discover what makes you, you; MyHeritage boasts you can discover where you really come from.

Hina Walajahi, from the National Institute of Health, warns:

While this hyperbolic 'it-will-change-your-life' marketing strategy is not unique to DTC genetic ancestry companies, it is distinct in the way it draws upon public faith in science and scientific authority to validate a causal relationship between genetic ancestry and personal identity.

Prof. Duster explores the powerful draw of these claims:

People have a thirst to believe; theres a real desire to know ones ancestry. For example, because of the history of slavery and because their history was erased, many African Americans in particular have a strong interest in tracing their ancestry back to Africa, in ways people from Europe dont quite have that because they had grandmothers and grandfathers to tell tales about what percent ancestry there is and so on."

But some people are anxious and thirsty for this kind of information, so theyre inclined to believe it as true because thats what they want to believe. This can lead to epistemological crises about who they are.

These crises are not uncommon, as this testimony demonstrates. However, some, like Prof. Duster, challenge placing nature (DNA) above nurture, arguing that:

This notion that, somehow, the DNA that you discover your 'real' biological mother or father is who you really are is an extraordinary leap away from the idea that you are, in part, the social networks that brought you up and that are around you.

Our CEO, Greg Powel, puts it best:

"I think the notion of your self-conception evolves over the course of your life. Youre shaped by a combination of your experiences and the people around you and your genetic make-up and who you are. I think thats who we are as people."

As Amy Sturm from the National Society of Genetic Counselors wisely told us: DNA is not destiny.

Most major direct-to-consumer DNA testing companies have clauses in their Privacy Terms intended to assure customers that their genetic data will not be shared or sold without their consent. In an effort to ensure this, these companies anonymize customers DNA samples, removing identifiable information like name and address when the sample is sent to the lab.

However, experts warn that genomic data is highly distinguishable, and that even a sequence of 30 to 80 SNPs [single-nucleotide polymorphisms, a.k.a. markers or variations] could uniquely identify an individual. In other words, anonymized genetic data can be re-identified:

"[A]s demonstrated by multiple recent studies, the risk of re-identification is strongly present. It was shown, in multiple independent studies, that it is possible to learn the identities of people who participate in research studies by matching their data with publicly available data. Fida K. Dankar, et al. in Human Genomics."

In addition, many DNA matching services are unavailable or limited if consumers do not willingly give up some of their privacy. For example, Ancestrys DNA Matches reminds customers that if you choose not to see your DNA matches or be listed as a match, some of the features included in your Ancestry subscription may not be available.

Privacy and data security concerns have been raised by other consumers, the media, politicians, and experts. These range from genetic data being sold or shared with pharmacological companies for the development of pharmaceuticals, to the potential risks of health or life insurance companies obtaining consumers genetic information and using it to raise their premiums or deny them services. This is because genetic data provides sensitive information about genetic conditions and predispositions to certain diseases such as cancer, Alzheimer's, and schizophrenia.

In her article Privacy of Information and DNA Testing Kits,Shanna Mason points that that submitting to genetic tests are not only exposing themselves to the risk of their genetic information getting into the wrong hands, but are also exposing information about shared familial risk. Masons article explores topics like genetic discrimination, and where the HIPAA and GINA privacy laws come into play.

Nonetheless, consumers are responsible for keeping up-to-date with how privacy terms and conditions are changed or modified over time, and continuing to use the services is treated as acceptance of these changes.

Screenshot from 23andme.com's Terms of Service. August 20, 2019.

Screenshot from 23andme.com's Terms of Service. August 20, 2019.

Additional concerns have also been raised concerning several aspects of law enforcement, including, but not limited to, the use of DNA databases to potentially racially profile suspects, the use of DNA databases in forensics, laws that allow police and federal officials to retain DNA samples even from non-charged suspects or acquitted individuals, and the general wide misunderstanding in legal situations of the limits of genomics.

Consumers also should be aware that DNA companies are legally obligated to submit data and documentation if faced with a warrant or subpoena. Moreover, some companies are openly working in tandemwith law enforcement institutions, and there arent any regulations to stop it.

Many direct-to-consumer DNA kits have expiry dates because of the stabilizing solution they contain. This solution or buffer is what prevents bacterial contamination during the shipping process.

Expiry dates are different for different companies, be it because theyre being overly cautious, or because their kits have longer lifespans than others. Of the ones we used with our DNA volunteers, only AncestryDNA did not have a clear expiry date on the kit itself. Those that did had very different dates, even though we requested them all at the same time:

We recommend that customers mail in their DNA samples at least within a year of receiving their kits in the mail.

Read more:
Top 10 DNA Testing of 2021 | ConsumersAdvocate.org

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