At home DNA tests can provide a large wealth of information about your genetics. Many companies now offer these tests, with a wide variety of results and information being analyzed. Some tests focus solely on ancestry, while others analyze aspects of your genes related to health, disease, fitness, or nutrition. While all of these tests use similar methods of correlating DNA data to various outcomes, not all tests are extremely useful.
To get the most out of your DNA test kit, you need to understand what results you are getting, how accurate and predictive those results are, and what you can do in spite of your genetics. Below is a thorough review of many different types of genetic tests, the results you can expect, and what you can do to take action on those items. Check it out!
Ancestry tests are one of the most popular types of DNA test kit. Companies like Ancestry, MyHeritage, and 23andMe offer the best ancestry tests which will analyze what gene variants you carry, and the results will correlate what genetic variants you carry with reference populations. A reference population is a group of people who have lived in a specific region for many generations.
Your results from an ancestry test can contain many things. You will likely receive a breakdown of your ethnicity. This percentage breakdown shows which populations your specific genetic variants likely came from. Tests from different companies can show different results because their reference populations are different. Some companies have large, well-researched reference populations, while others have small, insufficient reference populations. This accounts for differences in results from two companies.
In terms of acting on the results you get, you are fairly limited with an ancestry test. Ancestry tests are not related to any specific gene functions or outcomes. Instead, they are only looking at which variants are present, and which populations they match. Many companies specializing in ancestry test kits also offer a family tree service. With these services, you can build and explore your family history. Many companies also allow you to download your raw DNA file, which can be uploaded to other services to receive health or lifestyle analysis.
Carrier Status Tests
Carrier status genetic tests are some of the most scientifically sound, and they can provide you with great information when deciding to have children. A carrier status test will test genes which are known to be associated with genetic diseases, such as those for cystic fibrosis or Huntington’s disease. Although you may not show symptoms of these diseases, you may carry the genetic variants which lead to these diseases.
By determining which genetic variants you and your partner carry, you can accurately determine your chances of passing on those variants to your baby. For instance, if both you and your partner are carriers of the recessive gene for cystic fibrosis, you each have a 50% chance of passing that variant on to your child. If the child receives 2 of these disease-causing alleles, they will have cystic fibrosis. In other words, two people with recessive variants for cystic fibrosis will have a 25% chance of having a child with the disease. Carrier status tests cover a wide range of genetic diseases and can give you a very accurate prediction about what you can pass on.
Health and Disease Tests
Carrier status tests are specific to genetic diseases because these diseases are specifically linked to a certain gene malfunctioning. Many companies also offer tests which analyze your genetics and give you a report on how they may affect general health traits and increase your chances of other diseases. Unfortunately, these tests are not as accurate or predictive as carrier status tests.
Most health and disease traits are based on correlations. A correlation is simply a statistical connection between a disease or health outcome and a certain genetic variant. Since the advent of high-throughput genetic sequencing, scientists have been able to analyze large sample populations and see what diseases they get. Together, this allows them to identify genes which are commonly present in people with a certain condition. Sadly, few of these correlations have had the causation explained. In other words, the trait and the gene are connected, though we aren’t sure exactly how they affect each other.
That being said, health and disease tests are not entirely worthless. Certain traits and diseases have been shown to have a high correlation with certain genetic variants. Simply having one of these variants can increase or decrease your chance of experiencing a specific outcome. By knowing these results, you can work to counter your genetic predispositions with things like diet and exercise. However, you should also know that these tests are not a diagnosis. Even if they say you are at a lower risk for a disease or trait, you can still get that disease or display that trait. Genetics are enormously complex, and the science behind these reports is still developing.
Speaking of the complications within genetics, nutrition tests are notoriously bad at being predictive and helpful. Often, companies offering nutrition-based DNA analysis are basing their results on small-scale correlation studies, with no clear cause and effect relationship established. If you are interested and have the money, these tests can be entertaining and fun to take.
But, most of these companies simply pair your genetic results to generalized information on a good diet. While our genes do impact our diet, there is one diet which is generally good for all people. It is composed mostly of plant-based foods, minimally processed whole-foods, and contains a large variety of fruits and vegetables (similar to the average menu of meal kit services). However, nutrition-based DNA tests tend to hide this fact.
Instead, they will give you generalized information about weak correlations found within your genetics. For instance, you may receive the result that your body “craves more protein”, without a decent explanation of how much protein you should get. In fact, the typical “Western” diet consists of almost 50% protein. A healthier, plant-based diet consists of around 10% protein. Yet, if you got these results you may be tempted to eat more steak. If you are already eating a diet with 50% protein, you absolutely do not need any more protein. In fact, regardless of what your body craves, more protein could be detrimental to your health.
Like nutrition tests, many “fitness-based” DNA test kits market themselves as necessary tools for aspiring athletes. They claim that by knowing how your DNA affects your muscles, metabolism, and attributes, you can maximize your training regimen to become the best athlete possible. There is no doubt that genetics can play a role in your athleticism, just look at this article on Michael Phelps. However, like nutrition, it is not clear exactly how our genetics affect our athleticism, nor what percentage of athleticism is determined by practice, not genetics.
For example, one of the most commonly tested genetic “fitness” traits is related to your body’s production of muscle. Some muscles are fast-twitch, meaning they can contract and release quickly. Other muscles are slow-twitch, which don’t move as fast but have more endurance. It was once thought that people with mainly fast-twitch muscles would become sprinters, while those with slow-twitch muscles would become endurance runners.
What scientists have since found is that the makeup of muscles in your body is determined both by genetics, and what you commonly practice. Your muscles, if only used for endurance sports, will likely all become slow-twitch muscles over time. If you only sprint, they will change to fast-twitch fibers. Therefore, the utility of a genetic test for fitness is not much. At most, it can suggest what you might have to overcome to become the athlete you want to be.
Other Genetic Tests
A slew of other genetic tests is available for purchase on the internet. These range from genetic analysis of what types of wine you will like, to music curated specifically to your genetics. At most, these tests are entertaining. At worst, you are giving up your valuable genetic data to a company giving you nothing in return (and often charging you on top of that). Most of the companies offering these sorts of tests base their entire model on a tiny number of poorly designed studies. While tests like these may be more accurate and predictive in the future, they should likely be avoided for the time being.
The biggest takeaway from this article is that not all DNA test kits are created equally. Some, like carrier status tests, have been used for decades, are highly predictive, and give you actionable results. Others, like tests that claim to be able to predict which types of cheese you will enjoy, are worthless. Come back to this article at any time to review each type of test and determine if it will be worth your time and money.
Also remember: There is no such thing as a free lunch. Many of the “alternative” genetic tests are offered for free. But, the company is getting something out of the deal. Most likely, they are depersonalizing and aggregating your genetic data into a large dataset. Datasets like these are very valuable to pharmaceutical companies, insurance companies, and other entities in the healthcare section. Many “free” DNA testing companies make the majority of their income by selling these datasets.