© © Trunk Archive/Adrian Samson
January 9, 2026
Margit Hiebl
Find relatives, explore origins, or simply live healthier? Millions worldwide are using various genetic tests in search of their past—or their future.
"Meet your genes," says the casual invitation from provider 23andMe. And a cheerful, colorful group, portrayed by actors, introduces themselves personally: ACTN3, which affects muscle building; BTBD9, which affects movement during sleep; two others that increase the risk of celiac disease; and one that suggests an ancestor was a Viking. And so on.
The business of home genetic testing is booming. Providers like 23andMe, Ancestry, or MyHeritage are selling more DNA self-tests than ever and thus have one of the largest collections of human genomes. And it is highly lucrative: The global market, according to estimates by BIS Research, will grow to $6.4 billion by 2028, with an annual growth rate of 23 percent.
Not uninteresting: One of the founders of 23andMe is Anne Wojcicki, who comes from a family of scientists and grew up on the Stanford campus. One of her sisters, Susan, until recently the CEO of YouTube, once rented her garage to Larry Page and Sergey Brin, who founded Google there. Anne was married to the latter, who was also one of the first investors in 23andMe.
In the meantime, the pharmaceutical company GlaxoSmithKline acquired shares worth $300 million. The pedigree specialist Ancestry – originally founded to establish kinship ties between Mormons in the USA – has since been taken over by the US financial investor Blackstone, which may not have done this just to track down distant cousins. Because DNA data is the new gold. The major providers now also have German websites that comply with European data protection standards. Nevertheless, before deciding to send your DNA into the world, it is essential to research carefully and read exactly what you are consenting to.
The lure is the altruistic approach of becoming part of something larger and advancing the medicine of tomorrow. This is not necessarily untrue, as universities, foundations, and pharmaceutical companies in the USA are now cooperating. But you might only have material for party talk, whether you are ten percent Indian or Irish descent.
Critics also point out that the results from different providers vary significantly and are not valid enough. This is also because Direct-to-Consumer tests do not examine the entire genome, but only sample SNPs. Testing is done only through a saliva sample. For a genetic test in the lab, however, blood is usually taken, as it has more explanatory power, and in many cases, the entire genome is examined. This is reflected not only in the quality of the result but also in the price: While tests on the internet are available from 70 euros, sequencing the entire genome in the lab costs up to 3500 euros.
When it comes to ancestry or kinship, the light version works quite well. For deeper insights into the gene activity and how it influences the present or future, the lab version is certainly more informative. But do you really want to know everything? And what does it bring you then? "A genetic all-out strike is not always sensible and can bring more confusion than clarity," says Dr. Leon Holzscheiter, specialist in human genetics and laboratory medicine at Synlab MVZ in Munich.
It took 12 years as part of the international "Human Genome Project" to decipher our genetic information until it was established in 2003: 99.9 percent of all humans are identical. We differ only in 0.1 percent!
It all started with the Czech priest Gregor Mendel, who observed how the characteristics of red or white flowering plants are passed on from generation to generation. Today, everyone roughly knows what DNA looks like (keyword: double helix). This was discovered by the English chemist Rosalyn Franklin. In 1962, a Nobel Prize was awarded, unfortunately not to her, but to the molecular biologists Francis Crick and James Watson, who built on her results without her knowledge.
A small look into the microscope: When you look into a cell nucleus, you first see a kind of ball of yarn. When unraveled, you recognize 46 segments, the chromosomes. More precisely, 23 pairs – 22 identical and one that looks different in men and women. The two strands are held together by base blocks. There are four bases – adenine, thymine, cytosine, guanine – of which two always match. A with T and C with G. Our entire genome is written with these four letters. To read these sequences of letters, there were different approaches: In the 1970s, "Sanger sequencing" became established, named after the British biochemist Frederic Sanger, who also received a Nobel Prize for it.
Although still arduous, it led researchers in the "Human Genome Project" to their goal: Today we know that the genome consists of about three billion letter pairs. And we differ only in about every thousandth letter. These sites are called SNPs (Single Nucleotide Polymorphisms). They account for 90 percent of genetic differences.
"To assess what this variation does and whether it is decisive, reference data was needed, preferably from the largest possible data pool," says Leon Holzscheiter. Here, the human genome project significantly advanced research. What used to take 12 years is now read and compared with the reference genome in less than 12 hours using Next Generation Sequencing (NGS) – a technique that sequences DNA fragments in vast numbers in parallel. So much faster and more cost-effective. And still accurate.
Most people who take a genetic test want to know: Do I have it, will I get it, and can I do something about it? Simply put: It depends on how "hard" the genetic change is. The classic chromosome analysis is one of the clear genetic tests. Here, you can clearly see under the microscope whether there are changes in the structure or number of chromosomes.
Another example of a genetic test with very high predictive power is for diagnosing or predicting "Huntington's disease," an inherited neurological disorder that ultimately leads to death. "A predictive test on a healthy person can predict with 100 percent certainty whether one will develop it," says Holzscheiter. So far, it cannot be averted.
It is different with so-called "Actionable Genes," like the famous BRCA 1 and 2 genes. Pathogenic changes in these genes carry a high risk of developing breast or ovarian cancer. to develop. Risk means: can occur, but doesn't have to. Carriers of such genetic changes therefore have options for action.
Angelina Jolie decided to undergo a bilateral mastectomy due to her increased familial cancer risk. Many women followed her, also known as the "Jolie effect." Meanwhile, there has been a reassessment, and 12 additional genes associated with breast cancer have been well characterized. Basically, the focus is on intensified early detection and close monitoring. A genetic test helps in prevention.
Conversely, it is also true: "If the result of the examination is inconspicuous, it does not mean that a woman cannot develop breast cancer – it just means there is no evidence of a specific hereditary predisposition," explains human geneticist Holzscheiter.
Many diseases, such as Type 2 diabetes, are a combination of various small genetic changes – each not so serious by itself, but potentially problematic in sum – as well as external influences. This means there is a partly pronounced hereditary component, but whether the disease actually develops also strongly depends on lifestyle. The predictive value clearly lies in living healthier and thus to avert or delay a disease.
There are also genetic markers for Alzheimer's – but according to Holzscheiter, their predictive value is limited, as are the possibilities for intervention at the moment. Holzscheiter sees the problem that people are more likely to be scared by a statement. The significance of lifestyle genomics for determining biological age, for example, is also not yet conclusively clarified.
The methods for estimating biological age have so far been evaluated retrospectively. Whether a prediction comes true or a drug that is supposed to prolong life actually works will only be revealed prospectively in decades. “Therefore, markers are needed that convey this ad hoc or earlier. Whether the markers established so far actually measure what they are supposed to measure is still somewhat debatable,” says Holzscheiter.
Genetic tests can save lives, destroy them, or be the proverbial look into the crystal ball. What good does it do me to know that I have a gene variant, but can only tinker with symptoms? “Predictive genetics makes sense if you can do something about it,” explains Dr. Leon Holzscheiter. “To be able to treat diseases, you need to know the cause.” Although more and more causes are being understood, it is usually still not possible to treat them causally.
This is where the opportunity for the future lies: to find more and better genetically based intervention options. It starts with DNA and goes all the way to the specific drug in terms of personalized medicine. And of course, this also requires a good data basis – which should be handled with care.
On the other hand, there are ethical questions: How far and at what point may one intervene in the genome? But also: What does a positive test result do to a person? It is certain that interdisciplinary support is provided in genetic counseling – but it is now in your mind. “For some, it is important to know about a genetic predisposition, even if there are no intervention options yet, because they then shape their lives differently,” reports Holzscheiter.
And what if you don't want to know at all? “There is a right to not know at any time.” This right also includes not opening the envelope with the result. For example, if test findings also include statements about biological relatives.
Another danger seen by the German Reference Center for Ethics in the Life Sciences is a "geneticization" of the living world, where all differences between individuals are reduced to their DNA. And on the topic of aging, there is also the almost philosophical question: Is it a disease or simply a normal process of nature? And nature, according to human geneticist Holzscheiter, would have had no problem making us immortal.
"But it probably considered it more sensible not to let one organism live on forever, but to let life arise and disappear again and again through a combination or new pairing of genes." The thought of not being here forever has something comforting for him, who, incidentally, has not yet had a genetic test himself. "With immortality, one would probably eventually be forced to decide when one's own life should end. For me, a very unpleasant idea."
Not everyone likes to share their private data. Therefore, in Germany, data protection and the Genetic Diagnostics Act oversee laboratory genetic tests. Like all other medical data, those from genetic tests are also protected. They must be kept for 10 years and then destroyed. "Unless the patient requests them to be kept longer – then it's usually 30 years," says Leon Holzscheiter. When data is used for research purposes, such as studies, the participant must agree. Unfortunately, this is not always as transparent with tests sent abroad.
Genetic counseling in Germany may only be done by geneticists or specialists with the appropriate additional qualification. The counseling should be open-ended, meaning that it should provide enough information for patients to make their own decisions on how they want to be examined and treated, if necessary – then in consultation with the appropriate specialists. No one is left alone with difficult diagnoses, as there is an obligation for consultation with specialists, for example, from human genetics, neurology, or psychiatry.
Anyone wanting to have a genetic test should pay attention to the quality of the laboratory, advises human geneticist Dr. Leon Holzscheiter. A look at the website helps: The certificate from the German Accreditation Body DAkkS should be available there. There is also a guideline from the German Medical Association regulating quality standards for laboratories. A genetic test or diagnosis may not be required by an insurance company or an employer. This is to prevent genetic discrimination.
The cost of genetic tests varies greatly depending on the type and scope of the examination. Home DNA tests from providers like 23andMe or Ancestry are available for as little as 70 euros. However, these tests only randomly examine certain gene variants (SNPs). A full sequencing of the entire genome in the lab costs up to 3500 euros. Typically, blood is drawn, which offers more reliable results than just the saliva sample from home tests.
The reliability of home tests is limited, and the results from different providers can vary significantly. Direct-to-consumer tests do not examine the entire genome, but only randomly selected individual gene variants (SNPs). For questions about ancestry or relationships, these tests work quite well. However, for deeper insights into the genome and medically relevant statements, a professional lab test is significantly more informative and accurate.
The main difference lies in the method and scope of the examination. Home tests use saliva samples and analyze only selected gene variants. Lab tests use blood samples and can sequence the entire genome. In addition, laboratory tests include professional genetic counseling by qualified doctors, while home tests usually only provide automated reports. The quality and medical information value of lab tests is significantly higher, but this is also reflected in the price.
In Germany, laboratory genetic tests are subject to strict data protection regulations and the Genetic Diagnostics Act. Genetic data must be stored for at least 10 years and then destroyed unless you request longer storage (usually 30 years). For tests from international providers sent abroad, data security is often less transparent. The major providers now have German websites with European data protection standards, but you should carefully check what you are consenting to before sending your DNA.
Providers like 23andMe and Ancestry now own one of the largest collections of human DNA worldwide. This data is economically valuable: the pharmaceutical company GlaxoSmithKline, for example, has invested $300 million in 23andMe. The providers advertise that your data helps drive the medicine of tomorrow – through cooperation with universities and pharmaceutical companies. It is important that you read exactly what you are consenting to in terms of data usage before the test.
No, this is legally prohibited in Germany. Neither an insurer nor an employer is allowed to require a genetic test or the release of a diagnosis. This regulation is intended to exclude genetic discrimination and comprehensively protects your privacy.
This strongly depends on the type of genetic change. For some diseases like Huntington's disease, a genetic test can predict with 100 percent certainty whether the disease will break out. For so-called "actionable genes" like BRCA 1 and 2, the test shows an increased risk for breast or ovarian cancer – the disease may occur, but it does not have to. Many diseases like type 2 diabetes are a combination of multiple genetic factors and lifestyle. An inconspicuous test does not mean that you will definitely stay healthy – there is just no indication of a specific hereditary predisposition.
"Predictive genetics make sense if you can do something about it," explains human geneticist Dr. Leon Holzscheiter. A genetic test is particularly useful if there are options for action – for example, with BRCA genes, where intensive early detection and close monitoring are possible. For diseases like Alzheimer's, where the predictive value is limited and there are hardly any intervention options, a test can cause more anxiety than help. "A genetic all-round test is not always sensible and can cause more confusion than clarity."
If you want to have a professional genetic test performed, you should pay attention to the quality of the laboratory. Check the website to see if the certificate from the German Accreditation Body DAkkS is available. There is also a guideline from the German Medical Association that regulates quality standards for laboratories. In Germany, genetic counseling may only be carried out by geneticists or specialists with the appropriate additional qualifications. Get professional advice before and after the test.
The "Jolie effect" refers to the phenomenon that after Angelina Jolie’s public decision to undergo preventive bilateral breast amputation (mastectomy), many women followed suit. Jolie decided on this radical step due to her increased familial cancer risk from BRCA gene mutations. In the meantime, there has been a reassessment, and 12 other genes related to breast cancer have been characterized. Today, the focus is on intensified early detection and close monitoring instead of immediate surgery.
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