Y-STR Paternal Lineage Test - Y-Chromosome Testing

The Y-STR paternal lineage test is used to determine whether two or more males are related through their male lineage. The Y chromosome is passed from father to son and it remains the same through many generations because it has a relatively infrequent mutation rate. Thus, the Y-STR paternal lineage test can determine a father-son relationship, and the Y-STR test can also help to establish biological relationship between males in an extended family (like paternal half-brothers, paternal uncle, nephew, paternal grandfather, cousins, etc.).

The Y-STR test examines specific sites on the Y chromosome, and results in a unique Y-STR profile for each male tested. Males who are related through their fathers have the same Y-STR profiles, and males who are not related have different Y-STR profiles. Therefore, the Y-STR analysis is useful for excluding males from an alleged paternal lineage relationship. For example, in cases where the alleged father is missing and cannot be tested, Y-STR profiles of a male child and his alleged paternal uncle (biological brother of the missing alleged father) are compared. If the two Y-STR profiles of the tested males (child's Y-STR profile and alleged paternal uncle's Y-STR profile) do not match, then the missing alleged father (biologocal brother of the tested alleged uncle) very likely is not the biological father of the child (since brothers should have identical Y-STR profiles).

It is important to note that Y-STR paternal lineage test will not distinguish paternity to a child between two men who are in the same paternal lineage (e.g., this test will not distinguish paternity between two men who are related as brothers), since these two men have identical Y-STR profiles.