Y Chromosome Testing

A Y chromosome test, also known as a Y-STR* test or Y-DNA test, is used in cases where alleged male relatives wish to confirm they share a common paternal line. 

Most DNA relationship tests are carried out on the DNA which is inherited half from the child's mother and half from the child's father; this DNA is found in what are known as autosomal chromosomes (humans have 23 pairs of autosomal chromosomes). Each person also has two 'sex' chromosomes. Females have two X chromosomes while males have an X and a Y chromosome. Females do not have a Y chromosome.

All male children inherit their Y chromosome from their father; these children will in turn pass the Y chromosome that they have inherited from their father to their children when they become fathers.

This means it is possible to analyse and compare the DNA on the Y chromosome of two males to determine a biological relationship through the paternal family line. If the males in question are related, their Y chromosome will be identical.

*Y-STR is a short tandem repeat on the Y chromosome. 

A Y chromosome test is for male lineage. It cannot identify the nature of the relationship but will be conclusive as to whether or not the individuals share the same male lineage. So, if a more distant relationship is being tested, such as testing two males to determine if they are half siblings who share the same father, then a Y-STR test will show whether they have the same Y chromosome. If they do, this is consistent with them sharing the same biological father. If they have a different Y-STR profile this means that they cannot share the same biological father.

However, because all male relatives who share a common male lineage have the same Y chromosome, this type of testing cannot confirm the exact nature of the relationship. Therefore, if two siblings want to know if they share the same father, but the alternative father is the alleged father's full brother, then a Y chromosome test cannot help to establish this because the two potential fathers (being brothers) will have the same Y chromosome. 

All male family members who share a common male lineage have the same Y chromosome. Father and son, paternal uncle and nephew, paternal grandfather and grandson, full brothers, half-brothers sharing the same father, male cousins whose fathers are brothers, etc.

Most DNA relationship tests are carried out on the DNA which is inherited half from a child's mother and half from the child's father. This DNA is found in what are known as autosomal chromosomes (each person has 23 pairs of autosomal chromosomes).

A paternity test using the autosomal chromosomes is the most conclusive DNA test. A child will have inherited one DNA marker from their father (and one from their mother) for each DNA test and each child’s autosomal DNA profile will be different unless they are identical twins or triplets. This means that a standard DNA paternity test using autosomal DNA can provide a conclusive result with a high statistical probability. 

In addition to the autosomal chromosomes, each person also has two sex chromosomes. Females have two X chromosomes while males have an X and a Y chromosome. Females do not have a Y chromosome. 

A Y chromosome test is routinely used to establish male lineage in more distant relationship DNA tests. For example where the standard DNA test may not be able to establish the presence of the biological relationship due to the nature of inheritance of the DNA markers.

A Y chromosome test will show whether male individuals have the same Y-STR profile and therefore, the DNA result can provide evidence to support a claimed paternal relationship. However, it does not exclude other relationships (such as the father could be another male relative). If this is a possibility, then the Y chromosome test is not suitable. However, a standard autosomal DNA paternity test will be able to statistically differentiate between whether the tested man is the biological father of the child, or is a close relative of the child. 

Our standard Y chromosome testing charges are £324 +VAT for up to 2 individuals and then £133 +VAT per additional person.

Our testing prices include the following - as standard:

• All sampling kits and the cost of sending them to UK sampling locations.
• Pre-paid return envelopes to safely transport the samples to our laboratory.
• The cost of testing the samples once they have been received at our laboratory.
• The cost of producing and delivering the final paternity test results report.
• Our advice service for the duration of the case accessible via email, Freephone and our web Chat service.

Please note, for a court approved test, in addition to the DNA testing cost, you will also need to pay to have the DNA samples taken by an independent sample collector. Our customer services team can provide full details on how the sampling process works and the costs involved.

1. Register your DNA relationship testing requirements by phone or online.
2. We'll send sample collection kits to your chosen independent sampler.
3. On return of all the DNA test kits we immediately begin testing.
4. We will issue your test results report within 5 to 7 working days from receipt of your samples in our laboratories.