Y-Chromosome Testing

The Y-chromosome is only found in males and is the chromosome that determines sex.  A Y-chromosome is always found paired with an X-chromosome.  It is the chromosome which carries the genes for being male, specifically known as the SRY gene (sex determining region Y) and genes for fertility.  The fact that this chromosome is only found in males means that it is crucial when wanting to map out male lineage which is done in genetic testing by what is termed Y-STR testing. More about DNA Relationship Testing here.