Avuncular DNA Test

Avuncular DNA Test

Using an Aunt and Uncle DNA Test to Prove Paternity

Avuncular DNA testing is often used to confirm paternity when the alleged father is deceased, unavailable or unwilling to take part in a Paternity Test but his brother or sister is available. The test will establish the paternity of a child without testing the alleged father but using DNA samples from the alleged father’s full sibling instead. A father and his siblings will share common DNA and some of that common DNA will also be passed on to the father’s children. Thus, we can indirectly confirm that an untested, alleged father is the biological father of a child by comparing the DNA of his full sibling against that of the child.

Please note that we cannot test an aunt or uncle if they are not a full sibling to the alleged father (or mother) in question.

We are also able to determine paternity (or maternity) by testing paternal (or maternal) grandparents. Click here for more information about our Grandparent DNA Test.

The Science and Results of Aunt and Uncle DNA Testing

This DNA test determines the likelihood or statistical probability that the individuals tested are genetically related. When an Aunt and Uncle DNA Test is performed, the laboratory will determine the genetic profile of the alleged relatives based on the type of genetic material exhibited by each person, and an avuncular index is determined. If the avuncular index is less than 1.00, this indicates non-relatedness. If the avuncular index is greater than 1.00, this indicates that the two tested individuals are more likely to be true biological relatives. The higher the value of the avuncular index, the greater the likelihood that the two individuals are true biological relatives.

Members of the extended family including for example, aunts, uncles and grandparents share 25% of common DNA with their nieces, nephews or grandchildren. On the other hand, parents each share 50% of their DNA with their offspring. This means that a Paternity Test or Maternity Test can provide extremely high levels of accuracy (with a minimum probability of 99.99%); aunt/ uncle testing or even grandparent testing can never reach such high probabilities although results can provide a very strong indication of the alleged biological relationship.

Important Note to Increase Accuracy:

To increase the accuracy of an Aunt and Uncle DNA Test and provide the most accurate result, we ask that samples of a known parent should be included when possible. For example, the child’s mother should take part in the test if we are testing the alleged father’s sibling. Similarly, the child’s father should take part if the test is to prove maternity and the aunt or uncle is related on the mother’s side. There is no additional fee for including a known parent.

Are All Test Participants Male?

The Y chromosome is the sex determining chromosome in males and is only carried by males. In cases where tested parties are only male, we recommend doing a Y Chromosome Test. A Y Chromosome Test would provide a more conclusive result than an aunt or uncle test as all males descending for a common paternal ancestor share the same Y chromosome markers and the test result will be a simple Yes-or-No answer rather than a percentage probability.