Grandparents Day 2026: When a grandparent DNA test can provide answers

Grandparents Day (4 October) is a chance for families across the UK to celebrate the role grandparents play in their lives.

For most of us, that role is built on love, memories and time spent together. But for some families, the connection between a grandparent and grandchild carries a more practical significance, particularly when a child’s biological father or mother isn’t around, or isn’t willing, to confirm parentage.

In this blog, we explain the genetic relationship between grandparents and grandchildren, when a grandparent DNA test can provide answers, and how AlphaBiolabs’ accredited testing options work.

What is grandparent DNA testing?

Grandparent DNA testing is used to determine whether a child is biologically related to a potential grandparent.

Every child inherits 50% of their DNA from their biological mother and 50% from their biological father. That DNA is passed down again to the next generation, which means a grandchild typically shares around 25% of their DNA with each of their grandparents.

Because the relationship is once removed, the test works a little differently than a straightforward paternity or maternity test. Instead of a direct genetic match, our expert geneticists make a biostatistical calculation, known as the likelihood ratio for relatedness, to determine whether the tested individuals are biologically related.

There are three possible outcomes for a grandparent DNA test:

• A score of 10 or above is supportive, meaning there is very strong evidence that a relationship does exist
• A score between 0.1 and 9.9 is considered inconclusive, meaning it isn’t possible to determine whether a biological relationship exists
• A score of less than 0.1 is not supportive of a relationship

Learn more: Complex DNA relationship testing

When is a grandparent DNA test the right option?

A grandparent DNA test is often used when the potential parent of a child is unable to provide a DNA sample for a standard paternity or maternity test. If a biological father or mother has passed away, can’t be traced, or refuses to take part, testing a paternal or maternal grandparent can help verify the child’s parentage. 

This can be especially important in situations such as:

• Family disputes or uncertainty following a bereavement.
  For example, where questions arise about a child’s family connections after a parent has died.
• Blended or extended family situations.
  Such as a child having a step-grandparent they assumed was a biological relative, or where a family wants clarity on how a grandparent fits into the family tree.

• Informal kinship care arrangements.

  According to the Office for National Statistics (ONS), around 121,000 children in England and Wales were living in kinship care at the time of the 2021 census, and most of them (59.3%) lived with at least one grandparent.

  Where a grandparent steps in to care for a grandchild without the involvement of children’s services, either temporarily or long-term, an at-home grandparent DNA test can confirm a biological relationship, providing definitive answers before the family pursues a formal legal arrangement such as a special guardianship order or child arrangements order (which would require a legal DNA test).

A grandparent DNA test can also be useful in other scenarios, including:

• Confirming a family connection that has surfaced through adoption records or genealogy research.
• A grandparent seeking their own peace of mind about a biological connection to a grandchild.

Learn more: How to choose the right DNA test: a comprehensive guide

How does a grandparent DNA test work?

At AlphaBiolabs, grandparent DNA testing is a simple, non-invasive process. All that’s required is a cheek swab DNA sample from the child and the grandparent.

These samples are then analysed at our UKAS ISO 17025-accredited laboratory to identify matching DNA markers and calculate the likelihood ratio.

Our process for a peace of mind grandparent DNA test:

• Sample collection: Collect the DNA samples yourself at home, with our easy-to-use cheek swabs. No clinic visit required.
• Choice of test: Our standard test analyses 25 DNA markers, already ahead of the industry standard of 16-21. For customers who want the most powerful result available, our enhanced test analyses up to 45 markers, strengthening the statistical result and increasing the chance of a conclusive outcome.
• Laboratory analysis: Our expert geneticists compare the DNA profiles of everyone tested to calculate the likelihood ratio and determine the probability of a biological relationship.
• Turnaround: Results are available the next business day after your samples arrive at our laboratory.

It’s important to note that the results of an at-home DNA test are for your personal knowledge only, and the results cannot be used in court or for other official matters.

If you need a DNA test for legal or official reasons, you’ll need a legal DNA test.

For this type of test, chain of custody is followed throughout to ensure the results are legally admissible. This includes having one of our professional sample collectors take the DNA samples. They’ll also verify the identities of the sample donors and obtain consent from each person taking part, ensuring we have an electronic record of the entire process from sample collection through to delivery of your test results.

A legal grandparent DNA test can also be used to support family court proceedings, such as an application for a special guardianship or child arrangements order (as mentioned above).

Learn more: Peace of mind vs legal DNA tests<

How much does a grandparent DNA test cost?

An AlphaBiolabs Grandparent DNA Test starts from just £149, including your test kit and all lab fees.

The cost of the test includes testing for one potential grandparent and one grandchild. You also have the option to test more potential grandparents and grandchildren, or upgrade to our enhanced 45-marker test.

We also offer interest-free payment options including Klarna Pay in 3 and PayPal Pay in 3, so you don’t have to wait to get answers to your questions.

Why choose AlphaBiolabs for grandparent DNA testing?

When you’re exploring a family relationship, especially one where a parent isn’t available for paternity or maternity testing, you need results you can trust, from a lab that takes your privacy seriously.

At AlphaBiolabs, we specialise in at-home DNA testing for peace of mind, providing you with fast, accurate and affordable testing to help you better understand your biological connections.

• Versatile testing: Determine paternity or maternity when a parent is unavailable or unwilling to be tested, confirm a biological relationship for an informal kinship care arrangement, or get personal clarity on a family connection
• Rapid results: The next business day after your samples reach our lab
• Exceptional accuracy: Up to 45 DNA markers analysed, for a robust result
• Rigorous quality control: Our UKAS ISO 17025-accredited lab uses advanced technology and strict quality checks to maintain the highest level of precision and reliability
• All testing performed in the UK: So your samples are never sent abroad
• Decades of experience: 20+ years helping families find answers through at-home DNA testing
• 100% private and confidential: We’ll NEVER share your DNA results or data with any third-party organisations or DNA matching services
• Court-approved DNA testing available: All our relationship DNA tests can also be performed for court proceedings or other legal and official matters

Order your grandparent DNA test online now or contact us on 0333 600 1300 / info@alphabiolabs.com, and our friendly, discreet team can provide guidance on the best test to suit your needs.

You can also visit our Learning Centre to find out more about DNA testing.