The best way to determine whether two or more persons are half-siblings, full-siblings or non-related persons, is by direct testing of their parents if available (paternity/maternity test). If not, then persons that are recommended to participate (apart from the alleged siblings) are:

a) a parent (e.g. if the question is whether two persons have the same father*, then it is strongly recommended that their mother is also tested)
b) grandparents (e.g. if the question is whether two persons have the same father*, then it is strongly recommended that one or both parents of the father are also tested)
c) more siblings (e.g. if the question is whether two persons have the same father*, then it is strongly recommended that more siblings that share the same father* are also tested)

*the same is valid if the mother is under question

               
         Full Siblings                                   Half Siblings

Alternative:
a) If the siblings to be tested are male and the question is about whether they have the same father then a Y chromosome DNA analysis can be performed, in order to test the common paternal lineage.

               
          Full Siblings                                   Half Siblings 
     Υ Paternal Lineage                         Υ Paternal Lineage    

Alternative:
b) If the question is about whether two or more siblings have the same mother, then a mtDNA analysis can be performed in order to test the common maternal lineage. A mtDNA analysis is recommended only if the nuclear DNA is not enough or of bad quality.

                
         Full Siblings                                    Half Siblings 
 mtDNA Maternal Lineage                     mtDNA Maternal Lineage

For additional information, advice or order of the test please contact our laboratory.