5 DNA Test Myths: Sorting Fact from Fiction

DNA tests spark a great deal of curiosity—and quite a few fantasies. Between crime series scenes and personal stories, it’s easy to get confused. Here are five common misconceptions, explained simply, to help you understand what DNA tests can really offer and how to use them wisely.

You can take a DNA or paternity test at the pharmacy

The image persists: walk into a pharmacy, buy a test, and walk out with an answer. In reality, a DNA test involves several steps that always end at the lab. In concrete terms:

• you collect a sample following precise instructions (most often a cheek swab)

• you label and package the samples

• you send them to the lab

• at the lab, the DNA is extracted, then analyzed on dedicated platforms; quality controls and result interpretation are performed

The pharmacy does not perform any DNA extraction or genetic analysis. Depending on the country, it may distribute a sample collection kit, but the core of the work takes place in the lab. The key takeaway: the result is never “done on site,” it’s the outcome of a standardized and supervised technical process.

A single hair is enough—like in the movies

In movies, a single hair left on a brush cracks the case. In real life, it’s more nuanced. A hair without the root contains very little nuclear DNA—the kind needed for precise profile comparison. It may contain mitochondrial DNA, useful in some cases, but less definitive for establishing kinship. Even with the root, one hair may not provide enough usable material. That’s why:

• for most consumer tests, saliva remains the standard: it yields a lot of high-quality DNA

• when a lab accepts hair for specific analyses, it usually requests multiple hairs with root (for example, 5 to 10) to increase the chances of obtaining a usable profile

• for ancestry tests, saliva is the only accepted sample

The key message: if you have the option, follow the instructions and send a saliva sample. It’s simpler, more comfortable, and more reliable.

With my DNA alone, I can automatically find a family member

Your DNA doesn’t spit out a ready-made family tree. Labs compare your profile to their database of voluntary participants.

They detect matches and estimate the likely degree of kinship based on the amount of shared DNA. Then the real work begins:

• examining the closest matches

• communicating with them

• cross-referencing data with family trees, dates, locations, and records

Two points to keep in mind. First, it all depends on who is already in the database: without relatives enrolled, you’ll mostly get distant leads. Second, identifying a specific person takes time and involves as much traditional genealogy as DNA. These tests provide powerful clues—not guaranteed identities.

Ancestry tests give an exact, definitive ethnic map

Ancestry percentages are statistical estimates based on reference groups and algorithms. As those references expand and models evolve, your results may change—even though your DNA hasn’t.

It’s normal to see an 18% result become 22% after an update. Regional definitions also vary between labs: some areas are highly specific, while others cover broad historical regions with mixed populations.

Use these results as:

• a broad-scale orientation point

• a starting point for exploring family lines

• an indicator that can be refined over time

It’s fascinating and useful—but it’s not an official status or a fixed snapshot of your identity.

DNA tests are 100% infallible

Modern tests are very accurate, but they express results in terms of probability. In kinship testing, when the genetic markers match and the sample is of good quality, a probability of paternity over 99.9% is often obtained. That’s already extremely compelling. However, several factors influence the strength of a conclusion:

• the quality and quantity of DNA collected

• the number of markers analyzed

• the family configuration (for example, if one parent is absent, alternative strategies or more participants may be needed)

• the presence of close relatives among participants, which can complicate interpretation

In practice, a clear and solid result relies on a proper sample, a reputable lab, and—if needed—an adapted sampling strategy.