There are two major testing options for brother to brother DNA tests
Are you testing to see if you have the same father or the same mother (or both)?
Y chromosome DNA testing - Brothers testing for the same father
Accuracy of 99.9+%.
To see if two or more male persons have the same biological father. (If you wish to know if they have the same mother too, you will require a Full Sibling to Sibling DNA Test).
Only men have a Y chromosome, and a father will pass exactly the same Y chromosomal DNA to all his sons. Therefore, 2 brothers with the same biological father will always have exactly the same Y DNA patterns.
Note: If 2 men share the same Y chromosome, this shows that they share the same paternal line - so they could be father-son, uncle-nephew, cousins, etc.
Full sibling to sibling DNA testing. Brothers testing for the same mother and father
To establish whether or not two brothers have the same father and mother (please ask us about the mitochondrial test if you are trying to know if they just have the same mother).
Accuracy rate between 80 and 95%. Please note that the inclusion of the mother's (or mothers') samples in this testing procedure usually increases the accuracy rate and decreases the probability of getting an inconclusive result.
This test uses statistics analysis to evaluate the amount of DNA sharing and to deduce a biological relationship. For example, full siblings usually have more DNA in common than half siblings, while half siblings normally share more DNA than unrelated persons.
Any other relationship in the family besides the one you would like to verify by ordering this test (for example, an alleged half brother and half sister wanting to know if they have the same father and who have different mothers who are sisters between them) may change the result of this test. Please contact us if you think this might be your case.