Can sisters do a paternity test?

Paternity testing can be done between sisters, but the accuracy is lower than that between parents and children. Sister paternity testing mainly determines whether there is a blood relationship by comparing genetic markers on the X chromosome or autosomal chromosomes.

Paternity testing between sisters usually uses autosomal STR testing technology to analyze the matching of alleles at the two genetic loci. If they are full siblings from the same father and mother, about 50% of their genes are identical, and a large number of shared gene segments can be found during testing. If they are half-sisters from the same father or mother, the degree of genetic matching will be significantly reduced. Testing institutions generally collect oral mucosal cells or blood samples, extract DNA and perform high-throughput sequencing.

In special cases, it needs to be combined with X chromosome testing. When sisters are suspected of being half-mother, because the X chromosome only comes from the father, testing for specific markers on the X chromosome can improve the accuracy of the judgment. If the key regions of the X chromosomes between two people are completely inconsistent, the blood relationship from the same father can be ruled out. For half-sisters, mitochondrial DNA testing can be used as an auxiliary method because mitochondrial DNA is only inherited through the maternal line.

It is recommended to choose an institution with forensic qualifications for testing to ensure sampling standardization and result reliability. Before identification, it is necessary to confirm whether there is any special medical history such as bone marrow transplantation or blood transfusion that may affect DNA testing. The appearance, blood type and other characteristics of sisters in daily life can only be used as a reference, and the final conclusion should be based on the genetic testing report.