Can blood type be used to determine paternity?

Blood type cannot be used to determine paternity. The only way to determine paternity with 100% accuracy is with a DNA test.

In this article, we discuss paternity testing and why paternity cannot be confirmed using blood typing.

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What are the reasons for establishing paternity?

Because fathers usually play an important role in their child’s wellbeing and development, establishing a father-child bond early on has many benefits.

In situations where a man is uncertain whether he is the biological father of a child, he may be reluctant to spend time with them or contribute to their upbringing.

This can damage the chances of a positive parent-child relationship and cause emotional distress both to the potential father and to the child.

This is where paternity testing is useful, helping to ensure that the relationship between father and child gets off to the best possible start where the man is confirmed as the biological father.

There are many other good reasons why a person might want to find out who their biological father is, that have nothing to do with building a relationship between father and child.

These include:

• Where it is important for a person to know their full medical history – including their family history of certain diseases or health problems. This can be useful for couples/individuals trying to conceive, or for people who are simply curious about their health, and want to ensure any hereditary illnesses are diagnosed and treated as early as possible
• Developing a sense of identity – some psychologists believe that knowing your biological background is important in helping to establish a sense of identity

What are blood types?

Blood types are determined by the presence or absence of specific antigens on red blood cells. These antigens are classified using two main systems: the ABO system and the Rhesus (Rh) system.

ABO Blood Groups

• Type A – Has A antigens on red blood cells and produces anti-B antibodies in the plasma.
• Type B – Has B antigens and produces anti-A antibodies.
• Type AB – Has both A and B antigens and does not produce anti-A or anti-B antibodies, making it the universal recipient for ABO transfusions.
• Type O – Lacks A and B antigens but has both anti-A and anti-B antibodies, making it the universal donor for red blood cell transfusions.

Rhesus Factor

In addition to ABO classification, blood types are further categorised based on the Rhesus (Rh) factor.

If the Rh antigen is present, the blood type is Rh-positive (Rh⁺); if absent, it is Rh-negative (Rh⁻). For instance, a person with A blood type can be A+ or A-, depending on their Rh status.

How blood types are inherited

Each person inherits one ABO blood group allele from each biological parent. There are three possible alleles – A, B, and O.

• The A and B alleles are dominant, meaning they will be expressed if inherited.
• The O allele is recessive and is only expressed when a person inherits two O alleles (OO).

This means:

• Someone with blood type A could have the genotype AA or AO.
• Someone with blood type B could have the genotype BB or BO.
• Blood type AB means both A and B alleles are present.
• Blood type O means both alleles are O (OO).

Understanding blood types is essential in medical settings. In blood transfusions, mismatched blood can trigger immune reactions, leading to serious health risks. This is where knowing your blood type can be useful, especially in emergency medical situations.

Additionally, during pregnancy, Rhesus factor incompatibility between a mother and foetus can cause complications, requiring medical intervention. Knowledge of blood types also plays a role in forensic science and genetic research.

Can blood type be used to determine paternity?

Blood type could potentially be used to rule out a potential father, but it cannot be used to determine paternity. The only 100% accurate and reliable way of establishing paternity is with a paternity DNA test.

This is because a child’s blood type is inherited from both biological parents in a predictable way, based on the ABO and Rhesus blood group systems. However, many men could have a blood type that is compatible with a child’s, making it impossible to identify the father with certainty using blood typing alone.

Examples include:

• If a child has blood type O, but the mother has blood type A and the alleged father has blood type AB, he cannot be the biological father. This is because a person with blood type AB does not carry an O allele and therefore cannot pass on an O blood type.
• If a mother has blood type B and the child has type A, a father with type O could not be the biological father.

If a child’s blood type is compatible with the alleged father it does not prove he is the father, as many people share the same blood type. The only definitive way to verify paternity is with DNA testing.

What is the best way to establish paternity?

The best and most reliable way to establish paternity is with a DNA test.

For a peace of mind paternity test, cheek (buccal) swabs are used to collect cheek cell DNA from the alleged father(s) and the child.

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These samples can then be analysed and compared in the laboratory to identify matching DNA markers (loci) in the DNA samples.

Every person inherits half of their DNA from each of their biological parents, so such a comparison can help us to establish the probability of paternity.

When testing the biological father, both the man and the child will share enough identical sections of DNA to confirm a biological relationship. If the tested man is the biological father, the man and the child will share DNA at every tested marker. If the tested man is not the biological father, this will not be the case.

An AlphaBiolabs paternity DNA test looks at up to 45 DNA markers (loci) – double the industry standard for DNA testing – for a 100% accurate and reliable result.

Where can I get a paternity test?

AlphaBiolabs excels in offering fast, accurate, and reliable paternity testing using cheek (buccal) swabs – the industry-wide gold standard for relationship DNA testing,

Our DNA Paternity Test is the fastest and most popular DNA paternity test in Ireland, analysing up to 45 DNA markers for a 100% accurate result.

You can order an AlphaBiolabs Paternity Test online now, direct from our accredited laboratory, to receive results in just 2-3 days.*

Got questions about our paternity testing? Call our friendly and discreet Customer Services team on 01 402 9466 or email info@alphabiolabs.ie to discuss your requirements.

*Business days from receipt of samples into our laboratory, before 10am.