Paternity testing explained – what are DNA markers and how can they tell us who a child’s father is?

Paternity testing explained – what are DNA markers and how can they tell us who a child’s father is?

As a DNA testing laboratory, we are often asked how a paternity DNA test can prove who a child’s father is.

Whether you’re trying to find the best paternity test for you, or are simply curious about the science, you may want to know more about how paternity DNA tests are performed and how we can find out whether individuals are related simply by looking at their DNA.

Here, we’re getting back to basics to give you a better understanding of how a relationship DNA test works and what makes an AlphaBiolabs paternity test so accurate.

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The building blocks of DNA

Every human being is born with a DNA profile that is completely unique to them (except for identical twins, who share the same genetic material).

Each person inherits half of their genetic material from each of their parents, with mom and dad each passing half of their DNA profile to their children.

These profiles make up the building blocks of a person’s DNA.

In the laboratory, it is possible for DNA scientists to analyze the DNA of an individual and identify where a person shares matching ‘building blocks’ – alleles – with one or more people.

DNA markers that are shared between the tested individuals can determine whether they are related.

What are loci?

If you’ve been searching for a paternity test, you may have noticed that many testing laboratories will talk about the number of loci analyzed within the cost of the test.

Loci is in fact the scientific term for the locations of DNA markers within a strand of DNA.

In simple terms, think of a locus (plural loci) as a genetic street address of a DNA marker within the DNA strand.

Because loci are located on chromosomes and we inherit one chromosome from each of our parents, each locus (location in the DNA strand) is home to two alleles (one from each parent).

An AlphaBiolabs DNA test analyzes up to 42 DNA markers (loci) to determine whether two or more people are biologically related.

The more matching DNA markers we can find, the more likely it is that the individuals are related.

How can we find out who a child’s father is using a paternity test?

Now that you know how DNA can tell us who a child’s father is, here’s an example of how a paternity test works (if testing one child and one potential father):

  • Cheek (buccal) swabs are used to collect cheek cell DNA from the man and the child.
  • These samples are sent to AlphaBiolabs’ DNA laboratory for analysis by expert geneticists.
  • Both samples are analyzed and compared to one another. Our laboratory scientists will identify the alleles of up to 42 DNA markers (loci) within a strand of DNA and compare to find out how many matching DNA markers the man and the child share.
  • If the man is the biological father of the child, both the man and the child will share DNA at every marker tested to confirm a biological relationship.
  • If they do not share alleles at every tested DNA marker, it is unlikely the man is the biological father of the child.

An AlphaBiolabs paternity test analyzes up to 42 DNA markers making our paternity tests (and other relationship DNA tests) extremely accurate and conclusive.

The more DNA markers we can match, the more conclusive the proof that individuals are likely to be related.

Can an AlphaBiolabs DNA test look at a person’s genes?

An important thing to understand is that the area of DNA we are testing cannot tell us anything about a person’s physical characteristics such as their eye or hair color, or whether they have any genetic health issues.

Instead, our DNA tests look at Short Tandem Repeats (STRs) that are in an area of the genome known as non-coding or ‘junk’ DNA.

Within these STRs are short fragments of DNA which are repeated in a defined location within a chromosome.

When we’re doing a DNA test, AlphaBiolabs’ expert geneticists will look for variations in the number of repeats (alleles). Related people will have identical numbers of repeats.

Where can I buy a paternity test?

Now you know how a DNA test works, you can get the answers you need for just $109 with an AlphaBiolabs paternity DNA test.

All our tests are performed at our fully accredited laboratory, meeting the highest international quality standards.

We analyze up to 42 DNA markers (loci) for an extremely accurate result. Your secure, confidential results will be emailed to you in 3 business days from when the DNA samples arrive at our laboratory.

Order your paternity test now.

Alternatively, call our friendly and discreet Customer Services team on 727-325-2902 or email for more information.