More about this test

When carried out between female siblings, the X chromosome test will be able to assist you to determine whether you are:

  • Full sisters
  • Half sisters
  • Not related at all

X chromosome testing without the mother

In cases where two females have different mothers and want to confirm whether or not they share the same paternal father (thus, they wish to verify whether they are half- sisters or unrelated) they can carry out a motherless X chromosomes test. This means that they only need to submit their DNA samples and do not need the mother’s sample.

X chromosome testing with the mother

In cases where sisters have the same mother and question whether they share the same biological father (therefore want to determine whether they are full or half siblings), we can only carry out an X chromosome test with the mother’s sample. The mother’s DNA samples is necessary to map her X chromosome pattern and exclude it from the test, thereby, examining only the X chromosome inherited from the father.

If the mother is not willing to be tested or is simply not available, then a full siblings STR test will need to be done.

Grandmother and Granddaughter

The X chromosome test can be used between paternal grandmother and granddaughter as they must share one X chromosome. This shared X chromosome is the one that the grandmother passed to her son and he, in turn, passed to his daughter. We only need DNA samples of the paternal grandmother and granddaughter for this test. We require no other samples in this particular case.

An X chromosome test is done between siblings only in cases where a paternity DNA test cannot be carried out. In cases in which the alleged father’s DNA sample is available, a paternity test is recommended.

Sample collection for X chromosome testing

As soon as your order has been processed, the DNA sample collection kit will be sent to the address specified at the time of order. Kits will contain 4 mouth swabs per person, each packed into their own individual wrapper. All you need to do is rub the swabs inside the mouth for a few seconds and then allow them to dry. Click here for more information about DNA sample collection.


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