DNA paternity testing is based on the fact that each person’s unique gentic blueprint is stored in material known as DNA. This DNA determines everything about us as human beingsand is largely the same for all people. However, small differences in DNA between people determine each of our unique characteristics, including traits like eye color and blood type.There are also DNA differences that have no biological purpose, but which are useful for differentiating between or identifying people. Genetic markers for identity applications like paterenity testing or forensic identification use these types of non-functional genetic differences. One type of such markers are called Short Tandem Repeats (STRs) because they have varying numbers of repeated segments of DNA. Another type are called Single Nucleotide Polymorphisms (or SNPs) because they have a variation in only a sing DNA base.