X Chromosome Test - Sisters

When can I do a DNA test?


DNA testing is done by comparing the genetic profiles of two or more people. Alone, it is not possible to define a relationship or find who his father is for example. You must do the test with family members, if you do not have one, you must first find potential people who may be.


Follow our guide to discover the possibilities of  paternity search  or from  maternity research .


How to do a DNA test with a deceased person?


The complexity of the situation poses a serious technical and administrative problem. As a general rule, the consent of the person concerned must be previously and expressly obtained, otherwise no identification by genetic fingerprints can be carried out after death, but some countries allow it.  The second problem is the taking of samples from a deceased person, which remains a delicate operation. Exhumation is still possible under legal procedures, but samples may not provide enough genetic information. It is therefore possible to use non-standard samples for a private test.


What kind of sample can I use?


Laboratories always recommend the use of saliva as the primary sample. It is the easiest to provide and contains enough genetic information to perform all the tests. But if your situation does not allow you to use it, you can have recourse to other types of so-called non-standard samples such as hair, nails, blood ...


Non-standard samples always represent an additional cost to your order and have a degree of success which may vary according to several factors (conservation, date and method of collection, type of sample, etc.) We offer a list and advice on the 'use of  non-standard samples .


Does the reliability of my test depend on my samples?


No, reliability does not depend on the type of sample you are using or the method of collection. If you have results, it means that your samples provided enough genetic information for the test.

On the other hand, if your samples are not viable for the test or do not contain enough genetic information, the laboratory will warn you and ask you to send back other samples in order to continue the analyzes. In this case, the laboratory invoices the new analyzes, it is in this sense that it is important to choose the starting sample well.


Can we test from different addresses?


Yes, the laboratories always offer an option to send you several kits if the participants do not have the possibility to do the test together. This can also be done even if the participants are in different countries.

You can also, in order to avoid paying more than  create your own kit at home  in order to send it to the laboratory.


Can we come to the lab to do a test?


Usually no, the companies that offer you online testing are merchant companies that work in partnership with laboratories to outsource all procedural logistics and customer service. This allows the laboratory to concentrate only on the analytical work and so it is very rare that they provide a place open to the public. In addition, the sample collection that is requested does not require the intervention of a professional.


How can you be sure that the samples belong to the person concerned?


If you do a non-legal test and you doubt the origin of the samples, you will never be able to know only from the DNA profile whether the person who filed his name on the form is the same person who provided the samples.

In this case, you must organize yourself beforehand and put in the confidence of a doctor so that he is the guarantor of the samples and that he can verify the identity of the participants.

Under no circumstances should the participant be in contact with the samples. The kit should be sent to the doctor, who should return it to the laboratory.


Can a DNA test be reimbursed by Social Security?


No DNA tests are in any case considered as a medical act and reimbursed by social security, but some complementary health insurance offers it.

Therefore, pay attention to the offers of free DNA tests on the internet offering to go through the reimbursement of social security.


Can drug or drug consumption have a consequence on a DNA test?


No, no substance can alter a person's DNA. But the samples you send to the lab can be contaminated or degraded by many environmental factors. Take care to keep them in paper envelopes, avoid handling them with your fingers, especially not using a plastic bag.

Frequently Asked Questions

DNA relationship testing helps compare the genetic profile of two or more people to determine a common biological inheritance. Generally speaking, the test highlights the similarities and differences that make up your genetic makeup and assesses your match rate in order to give you results that match your relationship search.

In any case, this study cannot be established without putting different individuals in comparison, because your DNA is unique and does not contain the genetic profiles of your family, but only its heritage.

Do you want to remove any doubt about your biological origin or that of a loved one? But you don't know which test is best suited for your situation, follow our guide !! Information on DNA test we propose to orientate on possible tests currently putting you in the position of a paternity or maternity. Go ahead, it's simple and free and will allow you to already have solid information before contacting the laboratory that corresponds to you.

Which DNA test to choose ?

The DNA Relationship Test

The X chromosome is one of the two sex determining chromosomes. Its particularity is that it is present in all individuals in the human race, but only women have a double X chromosome, each from one of the parents.

The DNA test of  X chromosome  consists in analyzing the markers of this DNA, in order to define with great precision whether women share a paternal filiation link. It thus allows a search for paternity without the DNA of the presumed father.

What is an X chromosome test ?

You can do a DNA test to find out the parentage at home in a private setting. The order can be made directly on the internet from your home in order to receive the sampling equipment at home.

It often happens that the participants can be geographically distant, in this case the laboratories propose to send a genetic kit to each of the participants. 

Unfortunately it is still not possible to obtain
  a DNA test in a pharmacy , moreover only a laboratory with genetic analysis equipment and accredited by international standards can provide the result for a DNA test.

How to do an X chromosome test ?

Sibling DNA testing can be done with:

- Saliva samples (sterile buccal swabs)

- Non-standard samples: Like hair, nails, toothbrush...


Be careful, you must follow the instructions and respect the conditions so that the samples provide enough genetic information for your test.

What type of sample used for the test ?

In a paternal line, each child inherits from his father a perfectly identical and relatively unchanged sex chromosome over the generations.


In this context, all women from the same biological father share this gene in common.

In girls who have a double X chromosome, one of the X chromosomes necessarily comes from the mother and the other X chromosome is inherited from the father who himself inherited it from his own mother.


As this chromosome remains practically unchanged from generation to generation, genetic analysis makes it possible to verify whether two sisters come from the same biological father, even in the absence of their presumed father. ​​

By deduction, when a father transmits the  X chromosome to his daughter, he himself inherited from his biological mother. Thus it is possible to define a paternity with the DNA of the biological grandmother of the presumed father.

Who can participate in this parentage test ?

1. The two sisters have the same biological mother:


When the sisters share the same mother, it is essential that the mother also participates in the parentage test to obtain reliable and accurate results. Because this will allow the laboratory to isolate the maternal genes and thus focus on the X chromosomes that come from the father.  

If you are in doubt about motherhood between sisters or when it is not possible to provide a maternal sample, it is best to do a Sibling test .

2. The two sisters do not have the same biological mother (half-sister):

When  the sisters do not share the same mother, it is not necessary to provide DNA from the biological mother but only recommended. The results will still remain very reliable because the X chromosome from the father will be more easily detectable and compared between the half-sisters.

3. X chromosome test between Grandmother and Granddaughter:

A granddaughter and her paternal grandmother can take an X chromosome test to verify parentage to that paternal family line. The grandmother will have transmitted an X chromosome to her son, who will in turn have transmitted it to her daughter. This comparison gives a reliable and precise answer on the paternity of the granddaughter, even in the absence of her biological father.

The conditions concerning the analysis of the X chromosome : 


No, unfortunately it is not possible to do this test with cousins or other family members. The transmission of the X chromosome occurs randomly between children from the same biological mother. Thus it is possible that the X chromosome of a brother is not the same as his sister. It is then the same for transmission to uncles, aunts or cousins of the family.

Can we do an X chromosome test with cousins ?

Consent is the agreement you give to the laboratory to use your DNA for the purpose of carrying out a genetic analysis. It is mandatory if you wish to take a Brotherhood test. Consent can only be given explicitly by an adult and fully lucid person. This agreement must be in writing after having received informed information about the results of the test, by a contract or a consent form.


It is against the law to do a DNA test without the person's consent.

For minors, consent must be provided by one of the legal parents.

What is consent for a DNA test ?


Order your DNA test kit on the laboratory website


Receive your DNA kit



Take samples

at home


To return to




Discover your results

by email

DNA test procedure

X chromosome test participants


- An X chromosome test can be performed between the paternal grandmother and her granddaughter

- Two or more sisters can participate in the  test

- Sisters may or may not share the same biological mother (half-sister)

- The biological mother must participate under certain conditions

The Results of a DNA Test

- 5  at 7 days using buccal swabs for all participants

- 10 days minimum if one of the participants uses non-standard samples



This period is calculated from the moment your  samples arrive at the laboratory. Transport time is not taken into account.

What are the analysis times for a test between sisters ? 

The reliability and authenticity of the  X chromosome depends on several factors:

- The quality of the samples

- Laboratory accreditation

- The choice of the test according to the family situation

How reliable are the results ?

The quality of the DNA will depend on the collection and storage of the samples . It is therefore important to follow the instructions of the laboratory in order to ensure that you receive results.

Accredited laboratories meet the requirements relating to the analysis process, the management of resources and equipment, the impartiality and confidentiality of information. For an X chromosome test the laboratory must have ISO 17025 accreditation .

The reliability of the result depends on the number of genes compared. All the laboratories offer tests on an average of 15 to 22 genes (Loci STR) to make the comparison between the participants. Depending on your situation, you have the possibility to ask the laboratory for an extended comparison of the number of Loci. The extended comparison improves the precision and therefore the reliability of the results.

The results are presented in the form of a table:

- Each  column  corresponding to a participant

- Each line to a compared gene

- The composition of the gene is represented by one or two numbers/per person

How to read the results of genetic analysis ?

Genetic laboratory

The choice of laboratory is a very important step when you want to do a parentage test. You should know that not all laboratories offer the same services and depending on several  factors  it is better to make the choice that suits you.

You must choose a laboratory according to:  

- Your family situation and available participants

- The confidence that the laboratory inspires through customer feedback

- The transparency of the company concerning its activities and your expectations

How to choose a reliable Laboratory ?

Test Chromosome X
DNA Solution
5 jours
2 - 4 semaines
Participant Supplémentaire
+ 99€
+ 99€
Échantillon non standard
+ 59€
+ 75€

Maternal line research


The Mitochondrial DNA test allows anyone to compare this specific DNA from the biological mother to determine a common maternal lineage.

Paternal line research

The analysis of the Y chromosome makes it possible to define whether the grandfather and the grandson come from the same paternal line. By deduction if they are biologically related.