How does Home DNA Test Work?  – Genetic Education
What is home DNA test?

How does Home DNA Test Work? 

The home DNA test or home DNA test kit is a sample collection kit provided by the DNA testing company to a patient at home.

DNA tests are now gaining popularity very fast. The reason behind it is its accuracy. In modern trends, the DNA test is the most accurate personal testing facility available. 

The test is well known as gene test, DNA fingerprinting test, genetic test and many other names. But the purpose of it is to test the DNA. 

The DNA test is one of the most versatile techniques that use any bodily cell DNA to test, which gives ideas about the disease status, the genotypes and the identity of a person. 

There are so many different home DNA testing facilities and home DNA test kits are available in the market. DNA testing is popular among USA and UK people. Although people of developing countries like India, Pakistan and Bangladesh are still unaware of it. 

To understand how the home DNA test kit function, we need to understand what DNA testing is! And for that first, let me explain to you what DNA is! In the present article, we will understand what a DNA test is and how the home DNA test works. Also, I will give an insight into some of the popular home DNA testing kits.

Let us start the topic, 

Related article: How is Genetic Testing Done?- Explained.

DNA in a nutshell: 

DNA is the deoxyribose nucleic acid present in our cells. It’s a type of nucleic acid located in the nucleus. What does it do? It transfers information (biological) from parents to their child. 

For instance, your genetic makeup is inherited from your parents, half from your father and half from your mother. 

All the information for life to survive, reproduce, development and metabolic activities is tailored in our DNA. We can say, it’s a memory storage unit. Like our computer hard disk. 

The DNA is a long chain of nucleotides (now it is more technical!) made up of sugar, phosphate and nitrogenous bases. Adenine, thymine, cytosine and guanine are nitrogen bases of DNA; these are chemicals, just remember it. 

All the information is encoded in a triplet of nitrogenous bases and decoded into protein, the triplet is known as the genetic code.

A specific portion of DNA known as ‘gene’ manufactures proteins for us. The whole set of all the DNA of a single cell is denoted as a term, “Genome”. The genome comprises approximately 3.2 billion base pairs (a total of 6.4 billion bases). 

The genome is made up of genes and non-genes. This means the huge portion of our genome can’t form protein and are just sequence. 

Sequences of junk, non-functional and repetitive DNAs. Scientists test this region- the non-functional one, to know a person and to know someone’s identity. The repetitive sequences vary between individuals and are never similar. 

The difference in the number of repeats of different regions is the base of DNA tests. 

Note: No two people in the world are genetically similar.

Purpose and procedure of DNA test:

The DNA test is performed to 

  • To Identify a person 
  • To Criminal verification 
  • To Identify parents 
  • To know the disease status of a person 
  • Distinguish homozygous and heterozygous 

Related article: A Comparison Between Homozygous vs Heterozygous.

Comprehensively, DNA is obtained from a body sample and processed for DNA testing. A machine amplifies the DNA and quantifies the number of repeats present in a DNA sample. 

By comparing different samples we can identify different persons. The marker regions used in the amplification are the STR- short tandem repeats and VNTRs- variable number of tandem repeats. 

The image of paternity DNA testing.
The pictorial representation of paternity DNA testing with correct match and incorrect match.

How does a home DNA test work? 

You may wonder that using the home DNA test kit you can test DNA or generate your DNA report at home, right!

Well, it is not like that. 

The DNA testing technique required tedious sample preparation and instrumental steps to process DNA and is not possible at home. If you wish to do so, you have to invest at least 10000$ to 15,000$ to set up a DNA testing lab at home. 

Then you may wonder how actually a home DNA test works! Is it a scam? 

First, let me tell you, the home DNA testing facilities are now so common, therefore it is not a scam. 

See there are two types of sample collection procedures for any biological testing; Invasive and non-invasive. 

The invasive sample collection is a painful one, a sample is collected by making a hole or cutting a body part or skin or tissue. This means a person has to bear the pain. 

But in the non-invasive sample collection procedure, bodily samples that are available without cutting a tissue are recommended, for example, the saliva, or nasopharyngeal swab. 

It is not a painful process. 

The home DNA test kit is a non-invasive sample collection method. A person who is non-technical can collect the sample for DNA testing by themselves. So By using the home DNA test kit you no longer need to go to a genetic testing center. 

You can perform sample collection at home. 

In the home DNA test kit, a cotton swab and a collection tube are given. You just have to rub the cotton swab inside your chick and place it in the collection tube. 

A person from the lab takes back the collection kit and processes it for DNA testing. 

Steps and procedure: 

In the first step, order a DNA testing kit online which you wish to use. There are a lot of reviews and remarks online, you can make your decision by reading it. 

Once a kit reaches you, you have to follow these steps to collect a sample. 

Step 1: Open the sample collection kit, take first a consent form and fill it thoroughly. 

Taking yours’, your parent’s or your authority’s consent is very important for DNA testing. Consent information should have to be filled by the parents in case of testing for a child or minor. 

Step 2: Fill your personal information on the collection tube with the marker pen. Also mark a barcode sticker, if provided in the kit so that your identity remains disclosed and confirmed. 

Step 3: wash your hands cleanly and remove the swab from the package. Note that do not touch the swab or don’t touch it to any surface. It may cause false-positive results. 

Step 4: rub the buccal swab on the inner side of the cheek firmly for at least 1 minute. Do not rub it aggressively. Note that once the swab is taken out, don’t put it back in your mouth. 

Step 5: allow the swab to dry in a clean area, keep in mind that don’t let a swab touch anything. 

Step 6: Once the swab is dried, place it in the container. Place the container and the consent form back in the kit and send them to the testing center. 

You may expect results within a few weeks. 

Now move to the next segment of this article, you may think about what happened with the sample at the DNA testing lab! I am trying to explain it in simple language. 

At a lab or genetic laboratory whose home DNA test we ordered, first they derive the sample and store your information in a computer program based on the barcode readings. 

Now in the next step to check the DNA first using various chemical processes a DNA is snatched out from a cell. I am not explaining the DNA extraction process here, because it is a complicated chemical process. 

Once DNA from your saliva sample is isolated it is processed to determine its quality and quantity. Soon after the copies of DNA are obtained using a machine known as a thermocycler. 

After the amplification, the sequence information of the sample is derived if required and then cross-checked against the target sample. 

A special type of detection system known as electrophoresis separates different DNA markers of samples on a gel. 

Based on the results of gel electrophoresis, the probability of matching is determined. 

A genetic marker thing!!!

There are specific regions in our genome that are similar in sequence structure. But their number of repeats is different. For let say one sequence is 12 nucleotides long and repeatedly present in the genome. 

In one person, this specific region presents 50, in another person 90 and in the third person 120 times.

This means the structure of the DNA sequence is the same but its numbers are different. These types of sequences are known as markers or genetic markers and are widely used in DNA testing. 

To establish a relationship between two non-related people scientists are using approximately 12 to 21 different long and short markers, amplify and separate them. How different people have different repeat numbers, are explained in the figure below,

The short tandem repeat marker
The graphical illustration of the STR: short tandem repeats.

  Related article: Paternity DNA Test- Process, Results, Legal Proceeding and Cost.

Results of home DNA test: 

No two people in this world are genetically similar. Through genetic testing, 99.999% accuracy can be achieved. 

As we said, the copies sample or technically, ‘amplified’ DNA samples are run on an agarose gel or capillary electrophoresis to separate the fragments or markers. 

Now let me tell you that the results are a bit tricky if you are a non-technical person it is hard for you to understand the results of a home DNA test. 

In a gel for one particular marker two different DNA bands, referred to as the alleles are observed. 

One matches with the father, another with the mother. Because we know our DNA is inherited from our parents. 

A geneticist or PCR expert analyses the results carefully and sends them for generating the report.

A typical home DNA test report looks like this.

A typical result table of the different markers for the home DNA test.
A typical result table of the different markers for the home DNA test.

Here the table is of different DNA markers amplified during the test. The score of each marker is listed here. You can check that one marker allele will match with mother and one with father. 

Related article: DNA Fingerprinting- Definition, Steps, Methods and Applications.


The home DNA test is one of the easiest methods to test your DNA and it’s painless, though it is costlier. If you want to know who you are and from where you came, you can surely go for the DNA test.

There are so many good DNA testing facilities that are now available in the USA and UK also they let you understand the results as well.

Common FAQs: 

How does the home DNA test work? 

The home DNA test works on the principle of DNA amplification in which different DNA markers or repetitive regions are amplified and separated on a gel to validate the results. 

How accurate the home DNA test is? 

By using 21 to 64 different VNTR and STR markers 99.999% accuracy in DNA testing can be achieved. However, above 75% is also considered as accurate results in some countries. 

Can we do DNA tests at home? 

No. The home DNA test kit is only a sample collection Kit. We can collect a sample to test DNA. After collecting the sample non-invasively, the kit is sent back to the testing laboratory. 

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