Everything You Need to Know About Paternity Tests

Paternity tests are reliable scientific tools that confirm or exclude a biological link between an alleged father and a child. This article provides an accessible explanation of everything you need to know, from genetic analysis to the interpretation of results.

1. Sample Collection

The process begins with the collection of DNA samples using buccal swabs. These swabs are gently rubbed inside the cheek to collect cells containing DNA.

Why this method? It's quick, painless, and effective. 

Once the samples are collected, they are sent to a laboratory where the DNA is extracted and analyzed.

2. STR Loci Analysis: The Heart of the Test

The analysis relies on the study of STR loci (Short Tandem Repeats), specific regions of DNA that contain repetitive patterns. Each individual inherits half of their DNA from their mother and the other half from their father.

During the test, scientists compare the alleles (variants of the STR loci) of the child with those of the alleged father.

Example:
In a test result report, a locus such as D21S11 might show the following values:

• Child: 28, 30
• Mother: 28, 29
• Alleged Father: 30, 32

In this example, the 30 allele passed to the child comes from the alleged father. If, on the other hand, an allele is inherited from neither the mother nor the alleged father, paternity can be excluded.

Important fact: The analysis always includes several STR loci to ensure maximum accuracy.

3. Likelihood Ratio (Paternity Index)

The test result is based on the likelihood ratio or combined paternity index, which compares two hypotheses:

1. The probability that the tested man is the biological father.
2. The probability that an unrelated person is the father.

Concrete Example:
A likelihood ratio of 10,000 means that paternity is 10,000 times more likely than the alternative hypothesis.
When this ratio is very high, the probability of paternity typically exceeds 99.99%.

4. Interpretation of Results

The final report clearly indicates whether the alleged father is excluded or included as the biological parent:

• Exclusion of Paternity: If several STR loci do not match, paternity is excluded with 100% certainty.
• Inclusion of Paternity: If the STR loci match and the likelihood ratio is high, the probability of paternity exceeds 99.99%.

In Conclusion

Modern paternity tests, like those we offer at Adnà, combine scientific rigor with simplicity. Thanks to STR locus analysis and precise likelihood ratios, they provide reliable and clear answers to your questions of biological relation.

Discover our solutions at adnalacarte.com and find answers through your DNA.