DNA or DeoxyriboNucleic Acid is the molecule sometimes known as the blueprint to life.  DNA testing does not determine specific genetic diseases or disorders.  DNA testing can confirm that the two test participants share a common ancestor.

DNA testing for paternity is the most accurate test available with guaranteed results.  The average probability of paternity for DNA testing is greater than 99.99999%. 

There are three types of DNA testing:

yDNA for Genealogy - For testing males only (males have one x and one y chromosome).  The yDNA is passed down from father to son.  Females cannot take a yDNA test.

mtDNA for Genealogy - Both males and females can take this test.  Females carry a specific DNA material that is useful in genealogy called Mitochondria or mtDNA.  This is the material that surrounds the chromosomes.  The mtDNA is passed from the mother to her children.  Both males and females inherit mtDNA from their mother, but only females can pass it on.

atDNA Family Finder (Autosomal) - Both males and females carry autosomal DNA, which is inherited from both your parents.  Humans have 22 pairs of autosomal chromosomes and a pair of sex chromosomes (X and Y).  If two people share identical segments of DNA, they may share a recent ancestor.  The family finder determines relationships for up to five generations, but is not as useful in tracing a single surname line.