Why would I opt for this test?

Sisters may be unable to carry out a home paternity test if the father is deceased or unwilling/unable to be tested. An X chromosome test will in such cases allow you to establish whether you are:

  •     Half-sisters or full sisters
  •     Half-sisters or not sisters at all

X Chromosome Inheritance

The X chromosome test is possible because females receive one X chromosome from the mother and the other from the father. Therefore in the case where two sisters have different mothers, we can do an X chromosomes test without the need for the sample of the mother. The X chromosome test will therefore seek to establish whether they share the same X chromosome thus concluding they share the same father.

Two sisters that share the same mother and want to establish whether they are full siblings or half siblings will need to include their mother’s DNA sample alongside their own to be able to conclude the test. We will map the X chromosome pattern in the mother’s DNA sample and exclude this from the sisters’ DNA profile. We can then compare the remaining X chromosome pattern on the sisters’ DNA; if it matches it will indicate that they likely inherited their X chromosome from the same father. If the mother’s sample is not available then a siblings STR test is recommended.

Paternal 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.

The cost of an X chromosome test for two sisters is N/A with you results ready within 15 working days. Proceed to order your test using the option below or if you have any questions you can request a call-back free of charge!


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