Why Test the Mother in a Paternity Test?

In most paternity tests that we deal with the mother of the child is known. Therefore, we are sometimes asked: what is the benefit of testing the mother when it is possible to obtain a conclusive result even with only the father’s sample?  The answer:  including the sample of the mother in a DNA paternity test (and other DNA tests) will strengthen the final result of that test.

When can testing the mother be important?

Testing the mother is also very important in the case of DNA relationship tests such as for siblings, aunt/uncles and grandparents where the sample of the mother greatly increases the chance of obtaining a conclusive result.

A DNA paternity test compares 20 genetic markers of the alleged father to those of the child. If the alleged father is in fact the true biological father of the child, then all 20 genetic markers will match between the two profiles. If there are markers that do not match, then the alleged father will be excluded as the child’s paternal father. However, there are cases where a possible mutation may have occurred on one of the loci which may result in an inconclusive result. In such cases, the sample of the mother will assist to conclude the result as it will be able to confirm if the mutation is really a mutation or not.

Note: The laboratory extracts 21 genetic markers, not 20. However, the 21st marker is known as the amelogenin sex gene and establishes whether the sample being tested is a female DNA sample or a male DNA sample. Testing of this marker is a good precaution as sometimes clients make mistakes by, for example, labeling samples belonging to the alleged father as belonging to the mother or placing swabs belonging to the father in the mother’s envelope

What about relationship testing cases?

In relationship DNA testing, the mother’s sample is extremely useful. For example, in the case of a full siblings test, the sample of the mother will allow for the elimination of part of the genetic data that has to be compared between the two siblings, thereby, leaving the genetic markers inherited from the biological father for a more straightforward comparison, hence making the result more accurate.

At easyDNA we offer the opportunity to include the sample of the Mother at no extra cost. Therefore, if available, we strongly recommend that the sample of the mother is included when submitting your home DNA test.