Aunt or uncle DNA test

Checks whether someone is a child's biological aunt or uncle. Used when the possible father can't take part but his brother or sister can.

Also called
Avuncular test
Who takes part
The child and the father's full brother or sister, and the mother if available
Samples
Cheek swabs
Result
An avuncular index: how likely the relationship is
Court use
With a witnessed collection

How it works

A full brother or sister of the possible father shares about half his DNA. The lab compares their markers with the child's and reports how likely it is that they are the child's aunt or uncle, and so that their brother is the father.

How strong the result is

  • It is less certain than a paternity test or a grandparent test.
  • The child's mother taking part makes it clearer.
  • More than one full brother or sister of the father helps.
  • A half brother or half sister of the father gives a weak result.

When a grandparent test is better

If the father's parents are alive and willing, a grandparent DNA test gives a clearer answer.

Questions

What if the possible father has an identical twin?

Standard DNA tests can't tell identical twins apart, so the test can't say which twin is the father.

Can it be used in court?

Yes, with a witnessed collection, as in a legal test.

Guides for this test

  • Can you do a paternity test without the father?Yes: a lab can compare the child's DNA with the possible father's close relatives, and testing both of his parents gives the clearest answer. If he has died, a stored sample held by a medical facility, coroner or medical examiner may also work.
  • How do you read paternity test results?Look first at the probability of paternity and the conclusion. A result of 0% means the man tested is excluded as the biological father; 99% or more, backed by a large combined paternity index, means he is very likely the father.

Other tests