Fingerprinting like anything else in this world is not 100% perfect; it has its problems and uncertainties. Most people think that it like a real finger print it is totally unique well they are mistaken. The VNTR pattern can only show a chance that the child, father or criminal in question belongs. A person working in the crime lab only has a limited amount of DNA to work with most of the time and the
DNA has to be good. The DNA can be contaminated very easily. The DNA sample also can not to small or degraded. (Although
a process called PCR can be used to amplify the DNA sample.)
If the lab technician does find a good sample for a crime case they still have to prove their fact to the jury. Some people have a hard time with this because the DNA fingerprint is invisible to
the naked eye.