When genetics speaks: understanding Paternity testing

Discover how paternity tests work and how DNA analysis can determine a biological relationship with a very high degree of reliability.

Paternity tests are genetic analyses used to determine whether a biological relationship exists between an alleged father and a child.

These tests are based on the analysis of DNA (deoxyribonucleic acid), the genetic material that contains each person’s hereditary information and is virtually unique to every individual, with the exception of identical twins.

Today, when testing is performed using validated laboratory techniques and samples are correctly collected and identified, paternity tests provide a very high degree of reliability.

How does a paternity test work?

The analysis is primarily based on comparing specific genetic markers known as STRs (Short Tandem Repeats) between the child and the alleged father.

Each person inherits approximately half of their DNA from their mother and half from their father. The analysis of these genetic markers can therefore determine whether the variants found in the child are compatible with those of the alleged father.

The most commonly used samples are buccal swabs, which collect cells from the inside of the cheek, or saliva, depending on the procedure used by the laboratory. These methods are simple, quick and non-invasive.

When the genetic profiles are compatible across all the markers analysed, paternity can generally be established with a probability greater than 99.9%.

Types of paternity tests

• Informational or private test: intended strictly for personal use. It can establish whether a biological relationship exists between the participants but does not have legal validity.
• Legal or court-admissible test: performed according to specific identification and chain-of-custody procedures. The results may be used in administrative or legal proceedings in accordance with applicable regulations.
• Prenatal paternity test: used to assess paternity during pregnancy through specific techniques adapted to prenatal testing.

Is paternity testing reliable?

Yes. DNA analysis is one of the most reliable tools currently available for assessing biological relationships and is widely used in forensic genetics.

The reliability of the result mainly depends on:

• The quality and proper preservation of the sample.
• Correct identification of the participants.
• Appropriate sample collection and traceability.
• The use of validated laboratory procedures.
• Correct interpretation of the genetic results.

When can a paternity test be useful?

Paternity testing can be useful in a range of situations, both to resolve personal questions and in certain legal or administrative proceedings.

• Questions concerning biological parentage.
• Personal confirmation of family relationships.
• Legal or administrative proceedings, provided that the test meets the requirements for legal validity.

Conclusions

DNA-based paternity tests provide a very high level of accuracy when determining biological relationships.

Before carrying out a test, it is important to choose the appropriate type according to its intended purpose: an informational test for private use or a test that meets the necessary requirements for legal validity.

References

• Butler, J. M. (2023). Forensic DNA Typing: Biology, Technology, and Genetics of STR Markers. Academic Press.
• Gill, P., et al. (2022). DNA commission recommendations on interpretation of DNA evidence. Forensic Science International: Genetics.
• Jobling, M. A., & Gill, P. (2021). DNA in forensic analysis. Nature Reviews Genetics.
• OECD. (2023). Forensic DNA analysis: standards and best practices.

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